[v1,5/5] media: rkisp1: Add support for the companding block

From: Paul Elder <paul.elder@ideasonboard.com>

Add support to the rkisp1 driver for the companding block that exists on
the i.MX8MP version of the ISP. This requires usage of the new
extensible parameters format, and showcases how the format allows for
extensions without breaking backward compatibility.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
Changes since v0:

- Drop RKISP1_EXT_PARAM_BUFFER_V2
- Use common structure for compression and expansion curves
- Rename config fields in rkisp1_ext_params_*_config to just config
- Mention block type in structures documentation
- Constify arguments
- Replace __uxx types with uxx
- Use rkisp1_bls_swap_regs() helper in rkisp1_compand_bls_config()
- Use generic feature handling mechanism
---
 .../platform/rockchip/rkisp1/rkisp1-params.c  | 166 ++++++++++++++++++
 include/uapi/linux/rkisp1-config.h            |  85 ++++++++-
 2 files changed, 250 insertions(+), 1 deletion(-)

Hi Laurent
On Thu, Jul 04, 2024 at 01:25:33AM GMT, Laurent Pinchart wrote:
> From: Paul Elder <paul.elder@ideasonboard.com>
>
> Add support to the rkisp1 driver for the companding block that exists on
> the i.MX8MP version of the ISP. This requires usage of the new
> extensible parameters format, and showcases how the format allows for
> extensions without breaking backward compatibility.
>
> Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
> Changes since v0:
>
> - Drop RKISP1_EXT_PARAM_BUFFER_V2
> - Use common structure for compression and expansion curves
> - Rename config fields in rkisp1_ext_params_*_config to just config
> - Mention block type in structures documentation
> - Constify arguments
> - Replace __uxx types with uxx
> - Use rkisp1_bls_swap_regs() helper in rkisp1_compand_bls_config()
> - Use generic feature handling mechanism
> ---
>  .../platform/rockchip/rkisp1/rkisp1-params.c  | 166 ++++++++++++++++++
>  include/uapi/linux/rkisp1-config.h            |  85 ++++++++-
>  2 files changed, 250 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> index bac9d4972493..5865d53be9c8 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> @@ -57,6 +57,8 @@ union rkisp1_ext_params_config {
>  	struct rkisp1_ext_params_hst_config hst;
>  	struct rkisp1_ext_params_aec_config aec;
>  	struct rkisp1_ext_params_afc_config afc;
> +	struct rkisp1_ext_params_compand_bls_config compand_bls;
> +	struct rkisp1_ext_params_compand_curve_config compand_curve;
>  };
>
>  enum rkisp1_params_formats {
> @@ -1258,6 +1260,92 @@ rkisp1_dpf_strength_config(struct rkisp1_params *params,
>  	rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_DPF_STRENGTH_R, arg->r);
>  }
>
> +static void rkisp1_compand_write_px_curve(struct rkisp1_params *params,
> +					  unsigned int addr, const u8 *px_curve)
> +{
> +	size_t i, j;
> +	u32 val;
> +
> +	/*
> +	 * The compand curve is specified as a piecewise linear function with
> +	 * 64 points. X coordinates are stored as a log2 of the displacement
> +	 * from the previous point, in 5 bits, with 6 values per register. The
> +	 * last register stores 4 values.
> +	 */
> +	for (i = 0; i < 10; i++) {
> +		val = 0;
> +		for (j = 0; j < 6; j++)

This loops up to (9 * 6 + 5 = 59) and writes registers up to PX9
This should probably be i < 11 or <= 10 as the companding PX curve has
64 points and 10 registers.

Also, to make sure, I would define the number of PX() registers
entries instead of using the crude '10' and '6' values

> +			val |= ((px_curve[i * 6 + j] & 0x1f) << (j * 5));

Can't you just assign val without initializing it to 0 first and
or-ing it later ?

Also, once you make the external loop go up to 11, the last two
iterations will out-of-bound access px[64] and px[65] (px is declared
of size "RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES 64").

So this probably needs a check:

                if (i == 10 && j > 3)
                        break;

before accessing px_curve[], or maybe declare the for loop as

		for (j = 0; j < (i == 10 ? 4 : 6); j++)

> +		rkisp1_write(params->rkisp1, addr + (i * 4), val);

Then the parameteric macros
RKISP1_CIF_ISP_COMPAND_EXPAND_PX_N(n)
RKISP1_CIF_ISP_COMPAND_COMPRESS_PX_N(n)

are unused if not for the base address. Should you remove them and
only declare the base address value ?

> +	}
> +
> +	val = 0;
> +	for (j = 0; j < 4; j++)
> +		val |= ((px_curve[60 + j] & 0x1f) << (j * 5));

...

ok, I should maybe read the whole function before commenting. I left
the above comments there in case you want to unify the loop.

> +	rkisp1_write(params->rkisp1, addr + (i * 4), val);
> +}
> +
> +static void
> +rkisp1_compand_write_curve_mem(struct rkisp1_params *params,
> +			       unsigned int reg_addr, unsigned int reg_data,
> +			       size_t num_samples, const u32 *curve)

isn't the number of samples fixed to
RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES ?

> +{
> +	size_t i;

why a size and not an unsigned int ?
> +
> +	for (i = 0; i < num_samples; i++) {
> +		rkisp1_write(params->rkisp1, reg_addr, i);
> +		rkisp1_write(params->rkisp1, reg_data, curve[i]);
> +	}
> +}
> +
> +static void
> +rkisp1_compand_bls_config(struct rkisp1_params *params,
> +			  const struct rkisp1_cif_isp_compand_bls_config *arg)
> +{
> +	static const u32 regs[] = {
> +		RKISP1_CIF_ISP_COMPAND_BLS_A_FIXED,
> +		RKISP1_CIF_ISP_COMPAND_BLS_B_FIXED,
> +		RKISP1_CIF_ISP_COMPAND_BLS_C_FIXED,
> +		RKISP1_CIF_ISP_COMPAND_BLS_D_FIXED,
> +	};
> +	u32 swapped[4];
> +
> +	rkisp1_bls_swap_regs(params->raw_type, regs, swapped);
> +
> +	rkisp1_write(params->rkisp1, swapped[0], arg->r);
> +	rkisp1_write(params->rkisp1, swapped[1], arg->gr);
> +	rkisp1_write(params->rkisp1, swapped[2], arg->gb);
> +	rkisp1_write(params->rkisp1, swapped[3], arg->b);
> +}
> +
> +static void
> +rkisp1_compand_expand_config(struct rkisp1_params *params,
> +			     const struct rkisp1_cif_isp_compand_curve_config *arg)
> +{
> +	rkisp1_compand_write_px_curve(params, RKISP1_CIF_ISP_COMPAND_EXPAND_PX_N(0),
> +				      arg->px);
> +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_EXPAND_Y_ADDR,
> +				       RKISP1_CIF_ISP_COMPAND_EXPAND_Y_WRITE_DATA,
> +				       ARRAY_SIZE(arg->y), arg->y);
> +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_EXPAND_X_ADDR,
> +				       RKISP1_CIF_ISP_COMPAND_EXPAND_X_WRITE_DATA,
> +				       ARRAY_SIZE(arg->x), arg->x);

As the header reports

 * @x: Compand curve x-values. The functionality of these parameters are
 *     unknown to do a lack of hardware documentation, but these are left here

 is it safe to write them ?

> +}
> +
> +static void
> +rkisp1_compand_compress_config(struct rkisp1_params *params,
> +			       const struct rkisp1_cif_isp_compand_curve_config *arg)
> +{
> +	rkisp1_compand_write_px_curve(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_PX_N(0),
> +				      arg->px);
> +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_Y_ADDR,
> +				       RKISP1_CIF_ISP_COMPAND_COMPRESS_Y_WRITE_DATA,
> +				       ARRAY_SIZE(arg->y), arg->y);
> +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_X_ADDR,
> +				       RKISP1_CIF_ISP_COMPAND_COMPRESS_X_WRITE_DATA,
> +				       ARRAY_SIZE(arg->x), arg->x);
> +}
> +
>  static void
>  rkisp1_isp_isr_other_config(struct rkisp1_params *params,
>  			    const struct rkisp1_params_cfg *new_params)
> @@ -1844,6 +1932,66 @@ rkisp1_ext_params_afcm(struct rkisp1_params *params,
>  				      RKISP1_CIF_ISP_AFM_ENA);
>  }
>
> +static void rkisp1_ext_params_compand_bls(struct rkisp1_params *params,
> +					  const union rkisp1_ext_params_config *block)

nit: I presume going over 80-cols here is intentional

> +{
> +	const struct rkisp1_ext_params_compand_bls_config *bls =
> +		&block->compand_bls;
> +
> +	if (bls->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> +					RKISP1_CIF_ISP_COMPAND_CTRL_BLS_ENABLE);
> +		return;
> +	}
> +
> +	rkisp1_compand_bls_config(params, &bls->config);
> +
> +	if (!(params->enabled_blocks &
> +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS)))
> +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> +				      RKISP1_CIF_ISP_COMPAND_CTRL_BLS_ENABLE);
> +}
> +
> +static void rkisp1_ext_params_compand_expand(struct rkisp1_params *params,
> +					     const union rkisp1_ext_params_config *block)
> +{
> +	const struct rkisp1_ext_params_compand_curve_config *curve =
> +		&block->compand_curve;
> +
> +	if (curve->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> +					RKISP1_CIF_ISP_COMPAND_CTRL_EXPAND_ENABLE);
> +		return;
> +	}
> +
> +	rkisp1_compand_expand_config(params, &curve->config);
> +
> +	if (!(params->enabled_blocks &
> +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND)))
> +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> +				      RKISP1_CIF_ISP_COMPAND_CTRL_EXPAND_ENABLE);
> +}
> +
> +static void rkisp1_ext_params_compand_compress(struct rkisp1_params *params,
> +					       const union rkisp1_ext_params_config *block)
> +{
> +	const struct rkisp1_ext_params_compand_curve_config *curve =
> +		&block->compand_curve;
> +
> +	if (curve->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> +					RKISP1_CIF_ISP_COMPAND_CTRL_COMPRESS_ENABLE);
> +		return;
> +	}
> +
> +	rkisp1_compand_compress_config(params, &curve->config);
> +
> +	if (!(params->enabled_blocks &
> +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS)))
> +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> +				      RKISP1_CIF_ISP_COMPAND_CTRL_COMPRESS_ENABLE);
> +}
> +
>  typedef void (*rkisp1_block_handler)(struct rkisp1_params *params,
>  			     const union rkisp1_ext_params_config *config);
>
> @@ -1939,6 +2087,24 @@ static const struct rkisp1_ext_params_handler {
>  		.handler	= rkisp1_ext_params_afcm,
>  		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
>  	},
> +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS] = {
> +		.size		= sizeof(struct rkisp1_ext_params_compand_bls_config),
> +		.handler	= rkisp1_ext_params_compand_bls,
> +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> +		.features	= RKISP1_FEATURE_COMPAND,
> +	},
> +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND] = {
> +		.size		= sizeof(struct rkisp1_ext_params_compand_curve_config),
> +		.handler	= rkisp1_ext_params_compand_expand,
> +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> +		.features	= RKISP1_FEATURE_COMPAND,
> +	},
> +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS] = {
> +		.size		= sizeof(struct rkisp1_ext_params_compand_curve_config),
> +		.handler	= rkisp1_ext_params_compand_compress,
> +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> +		.features	= RKISP1_FEATURE_COMPAND,
> +	},
>  };
>
>  static void rkisp1_ext_params_config(struct rkisp1_params *params,
> diff --git a/include/uapi/linux/rkisp1-config.h b/include/uapi/linux/rkisp1-config.h
> index 00b09c92cca7..dd962df53af5 100644
> --- a/include/uapi/linux/rkisp1-config.h
> +++ b/include/uapi/linux/rkisp1-config.h
> @@ -164,6 +164,11 @@
>  #define RKISP1_CIF_ISP_DPF_MAX_NLF_COEFFS      17
>  #define RKISP1_CIF_ISP_DPF_MAX_SPATIAL_COEFFS  6
>
> +/*
> + * Compand
> + */
> +#define RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES	64
> +
>  /*
>   * Measurement types
>   */
> @@ -851,6 +856,39 @@ struct rkisp1_params_cfg {
>  	struct rkisp1_cif_isp_isp_other_cfg others;
>  };
>
> +/**
> + * struct rkisp1_cif_isp_compand_bls_config - Rockchip ISP1 Companding parameters (BLS)
> + * @r: Fixed subtraction value for Bayer pattern R
> + * @gr: Fixed subtraction value for Bayer pattern Gr
> + * @gb: Fixed subtraction value for Bayer pattern Gb
> + * @b: Fixed subtraction value for Bayer pattern B
> + *
> + * The values will be subtracted from the sensor values. Note that unlike the
> + * dedicated BLS block, the BLS values in the compander are 20-bit unsigned.

I presume it's not worth mentioning this feature is only supported on
specific platforms, right ?

> + */
> +struct rkisp1_cif_isp_compand_bls_config {
> +	__u32 r;
> +	__u32 gr;
> +	__u32 gb;
> +	__u32 b;
> +};
> +
> +/**
> + * struct rkisp1_cif_isp_compand_curve_config - Rockchip ISP1 Companding
> + * parameters (expand and compression curves)

Here and below: multi-line comments are aligned differently in the
rest of the file

* struct rkisp1_cif_isp_compand_curve_config - Rockchip ISP1 Companding
*                                              parameters (expand and compression curves)

> + * @px: Compand curve x-values. Each value stores the distance from the
> + *      previous x-value, expressed as log2 of the distance on 5 bits.
> + * @x: Compand curve x-values. The functionality of these parameters are
> + *     unknown to do a lack of hardware documentation, but these are left here

s/unknown to/unknown due to/

> + *     for future compatibility purposes.

Also, the documentation of struct members in the existing code doesn't
use '.' at the end (not totally true, some do, so up to you)


> + * @y: Compand curve y-values
> + */
> +struct rkisp1_cif_isp_compand_curve_config {
> +	__u8 px[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> +	__u32 x[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> +	__u32 y[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> +};
> +
>  /*---------- PART2: Measurement Statistics ------------*/
>
>  /**
> @@ -1018,6 +1056,9 @@ struct rkisp1_stat_buffer {
>   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_HST_MEAS: Histogram statistics
>   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_AEC_MEAS: Auto exposure statistics
>   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_AFC_MEAS: Auto-focus statistics
> + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS: BLS in the compand block
> + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND: Companding expand curve
> + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS: Compandding compress curve

s/Compandding/Companding/

>   */
>  enum rkisp1_ext_params_block_type {
>  	RKISP1_EXT_PARAMS_BLOCK_TYPE_BLS,
> @@ -1037,6 +1078,9 @@ enum rkisp1_ext_params_block_type {
>  	RKISP1_EXT_PARAMS_BLOCK_TYPE_HST_MEAS,
>  	RKISP1_EXT_PARAMS_BLOCK_TYPE_AEC_MEAS,
>  	RKISP1_EXT_PARAMS_BLOCK_TYPE_AFC_MEAS,
> +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS,
> +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND,
> +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS,
>  };
>
>  /**
> @@ -1384,6 +1428,42 @@ struct rkisp1_ext_params_afc_config {
>  	struct rkisp1_cif_isp_afc_config config;
>  } __attribute__((aligned(8)));
>
> +/**
> + * struct rkisp1_ext_params_compand_bls_config - RkISP1 extensible params
> + * Compand BLS config

Here and in other places 'Compand' is spelled with capital 'C'. Is it
intentional ?

> + *
> + * RkISP1 extensible parameters Companding configuration block (black level
> + * subtraction). Identified by :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS`.
> + *
> + * @header: The RkISP1 extensible parameters header, see
> + *	    :c:type:`rkisp1_ext_params_block_header`
> + * @config: Companding BLS configuration, see
> + *	    :c:type:`rkisp1_cif_isp_compand_bls_config`
> + */
> +struct rkisp1_ext_params_compand_bls_config {
> +	struct rkisp1_ext_params_block_header header;
> +	struct rkisp1_cif_isp_compand_bls_config config;
> +} __attribute__((aligned(8)));
> +
> +/**
> + * struct rkisp1_ext_params_compand_curve_config - RkISP1 extensible params
> + * Compand curve config
> + *
> + * RkISP1 extensible parameters Companding configuration block (expand and
> + * compression curves). Identified by
> + * :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND`or
> + * :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS`.
> + *
> + * @header: The RkISP1 extensible parameters header, see
> + *	    :c:type:`rkisp1_ext_params_block_header`
> + * @config: Companding curve configuration, see
> + *	    :c:type:`rkisp1_cif_isp_compand_curve_config`
> + */
> +struct rkisp1_ext_params_compand_curve_config {
> +	struct rkisp1_ext_params_block_header header;
> +	struct rkisp1_cif_isp_compand_curve_config config;
> +} __attribute__((aligned(8)));
> +
>  #define RKISP1_EXT_PARAMS_MAX_SIZE					\
>  	(sizeof(struct rkisp1_ext_params_bls_config)			+\
>  	sizeof(struct rkisp1_ext_params_dpcc_config)			+\
> @@ -1401,7 +1481,10 @@ struct rkisp1_ext_params_afc_config {
>  	sizeof(struct rkisp1_ext_params_awb_meas_config)		+\
>  	sizeof(struct rkisp1_ext_params_hst_config)			+\
>  	sizeof(struct rkisp1_ext_params_aec_config)			+\
> -	sizeof(struct rkisp1_ext_params_afc_config))
> +	sizeof(struct rkisp1_ext_params_afc_config)			+\
> +	sizeof(struct rkisp1_ext_params_compand_bls_config)		+\
> +	sizeof(struct rkisp1_ext_params_compand_curve_config)		+\
> +	sizeof(struct rkisp1_ext_params_compand_curve_config))

Do we need a comment to say why there are two entries of the same
type or not ?

>
>  /**
>   * enum rksip1_ext_param_buffer_version - RkISP1 extensible parameters version
> --
> Regards,
>
> Laurent Pinchart
>

On Thu, Jul 04, 2024 at 12:40:42PM +0200, Jacopo Mondi wrote:
> Hi Laurent
> On Thu, Jul 04, 2024 at 01:25:33AM GMT, Laurent Pinchart wrote:
> > From: Paul Elder <paul.elder@ideasonboard.com>
> >
> > Add support to the rkisp1 driver for the companding block that exists on
> > the i.MX8MP version of the ISP. This requires usage of the new
> > extensible parameters format, and showcases how the format allows for
> > extensions without breaking backward compatibility.
> >
> > Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> > Changes since v0:
> >
> > - Drop RKISP1_EXT_PARAM_BUFFER_V2
> > - Use common structure for compression and expansion curves
> > - Rename config fields in rkisp1_ext_params_*_config to just config
> > - Mention block type in structures documentation
> > - Constify arguments
> > - Replace __uxx types with uxx
> > - Use rkisp1_bls_swap_regs() helper in rkisp1_compand_bls_config()
> > - Use generic feature handling mechanism
> > ---
> >  .../platform/rockchip/rkisp1/rkisp1-params.c  | 166 ++++++++++++++++++
> >  include/uapi/linux/rkisp1-config.h            |  85 ++++++++-
> >  2 files changed, 250 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> > index bac9d4972493..5865d53be9c8 100644
> > --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> > +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> > @@ -57,6 +57,8 @@ union rkisp1_ext_params_config {
> >  	struct rkisp1_ext_params_hst_config hst;
> >  	struct rkisp1_ext_params_aec_config aec;
> >  	struct rkisp1_ext_params_afc_config afc;
> > +	struct rkisp1_ext_params_compand_bls_config compand_bls;
> > +	struct rkisp1_ext_params_compand_curve_config compand_curve;
> >  };
> >
> >  enum rkisp1_params_formats {
> > @@ -1258,6 +1260,92 @@ rkisp1_dpf_strength_config(struct rkisp1_params *params,
> >  	rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_DPF_STRENGTH_R, arg->r);
> >  }
> >
> > +static void rkisp1_compand_write_px_curve(struct rkisp1_params *params,
> > +					  unsigned int addr, const u8 *px_curve)
> > +{
> > +	size_t i, j;
> > +	u32 val;
> > +
> > +	/*
> > +	 * The compand curve is specified as a piecewise linear function with
> > +	 * 64 points. X coordinates are stored as a log2 of the displacement
> > +	 * from the previous point, in 5 bits, with 6 values per register. The
> > +	 * last register stores 4 values.
> > +	 */
> > +	for (i = 0; i < 10; i++) {
> > +		val = 0;
> > +		for (j = 0; j < 6; j++)
> 
> This loops up to (9 * 6 + 5 = 59) and writes registers up to PX9
> This should probably be i < 11 or <= 10 as the companding PX curve has
> 64 points and 10 registers.
> 
> Also, to make sure, I would define the number of PX() registers
> entries instead of using the crude '10' and '6' values
> 
> > +			val |= ((px_curve[i * 6 + j] & 0x1f) << (j * 5));
> 
> Can't you just assign val without initializing it to 0 first and
> or-ing it later ?

I'm not sure to see what you mean here.

> Also, once you make the external loop go up to 11, the last two
> iterations will out-of-bound access px[64] and px[65] (px is declared
> of size "RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES 64").
> 
> So this probably needs a check:
> 
>                 if (i == 10 && j > 3)
>                         break;
> 
> before accessing px_curve[], or maybe declare the for loop as
> 
> 		for (j = 0; j < (i == 10 ? 4 : 6); j++)
> 
> > +		rkisp1_write(params->rkisp1, addr + (i * 4), val);
> 
> Then the parameteric macros
> RKISP1_CIF_ISP_COMPAND_EXPAND_PX_N(n)
> RKISP1_CIF_ISP_COMPAND_COMPRESS_PX_N(n)
> 
> are unused if not for the base address. Should you remove them and
> only declare the base address value ?

I think it's useful to document what's available in terms of register
macros, even if not everything is used.

> > +	}
> > +
> > +	val = 0;
> > +	for (j = 0; j < 4; j++)
> > +		val |= ((px_curve[60 + j] & 0x1f) << (j * 5));
> 
> ...
> 
> ok, I should maybe read the whole function before commenting. I left
> the above comments there in case you want to unify the loop.

I'll try to rework the code.

> > +	rkisp1_write(params->rkisp1, addr + (i * 4), val);
> > +}
> > +
> > +static void
> > +rkisp1_compand_write_curve_mem(struct rkisp1_params *params,
> > +			       unsigned int reg_addr, unsigned int reg_data,
> > +			       size_t num_samples, const u32 *curve)
> 
> isn't the number of samples fixed to
> RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES ?

A previous version of the patch had two macros for the expand and
compress curves. Now that it's unified, I can drop the argument.

> > +{
> > +	size_t i;
> 
> why a size and not an unsigned int ?

The patch is originally from Paul, I don't know. I'll switch to unsigned
int as size_t is 64-bit on 64-bit platforms, which is overkill.

> > +
> > +	for (i = 0; i < num_samples; i++) {
> > +		rkisp1_write(params->rkisp1, reg_addr, i);
> > +		rkisp1_write(params->rkisp1, reg_data, curve[i]);
> > +	}
> > +}
> > +
> > +static void
> > +rkisp1_compand_bls_config(struct rkisp1_params *params,
> > +			  const struct rkisp1_cif_isp_compand_bls_config *arg)
> > +{
> > +	static const u32 regs[] = {
> > +		RKISP1_CIF_ISP_COMPAND_BLS_A_FIXED,
> > +		RKISP1_CIF_ISP_COMPAND_BLS_B_FIXED,
> > +		RKISP1_CIF_ISP_COMPAND_BLS_C_FIXED,
> > +		RKISP1_CIF_ISP_COMPAND_BLS_D_FIXED,
> > +	};
> > +	u32 swapped[4];
> > +
> > +	rkisp1_bls_swap_regs(params->raw_type, regs, swapped);
> > +
> > +	rkisp1_write(params->rkisp1, swapped[0], arg->r);
> > +	rkisp1_write(params->rkisp1, swapped[1], arg->gr);
> > +	rkisp1_write(params->rkisp1, swapped[2], arg->gb);
> > +	rkisp1_write(params->rkisp1, swapped[3], arg->b);
> > +}
> > +
> > +static void
> > +rkisp1_compand_expand_config(struct rkisp1_params *params,
> > +			     const struct rkisp1_cif_isp_compand_curve_config *arg)
> > +{
> > +	rkisp1_compand_write_px_curve(params, RKISP1_CIF_ISP_COMPAND_EXPAND_PX_N(0),
> > +				      arg->px);
> > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_EXPAND_Y_ADDR,
> > +				       RKISP1_CIF_ISP_COMPAND_EXPAND_Y_WRITE_DATA,
> > +				       ARRAY_SIZE(arg->y), arg->y);
> > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_EXPAND_X_ADDR,
> > +				       RKISP1_CIF_ISP_COMPAND_EXPAND_X_WRITE_DATA,
> > +				       ARRAY_SIZE(arg->x), arg->x);
> 
> As the header reports
> 
>  * @x: Compand curve x-values. The functionality of these parameters are
>  *     unknown to do a lack of hardware documentation, but these are left here
> 
>  is it safe to write them ?

Yes. They don't seem to have an effect, but they're written.

> > +}
> > +
> > +static void
> > +rkisp1_compand_compress_config(struct rkisp1_params *params,
> > +			       const struct rkisp1_cif_isp_compand_curve_config *arg)
> > +{
> > +	rkisp1_compand_write_px_curve(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_PX_N(0),
> > +				      arg->px);
> > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_Y_ADDR,
> > +				       RKISP1_CIF_ISP_COMPAND_COMPRESS_Y_WRITE_DATA,
> > +				       ARRAY_SIZE(arg->y), arg->y);
> > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_X_ADDR,
> > +				       RKISP1_CIF_ISP_COMPAND_COMPRESS_X_WRITE_DATA,
> > +				       ARRAY_SIZE(arg->x), arg->x);
> > +}
> > +
> >  static void
> >  rkisp1_isp_isr_other_config(struct rkisp1_params *params,
> >  			    const struct rkisp1_params_cfg *new_params)
> > @@ -1844,6 +1932,66 @@ rkisp1_ext_params_afcm(struct rkisp1_params *params,
> >  				      RKISP1_CIF_ISP_AFM_ENA);
> >  }
> >
> > +static void rkisp1_ext_params_compand_bls(struct rkisp1_params *params,
> +					  const union rkisp1_ext_params_config *block)
> 
> nit: I presume going over 80-cols here is intentional

I think so :-)

> > +{
> > +	const struct rkisp1_ext_params_compand_bls_config *bls =
> > +		&block->compand_bls;
> > +
> > +	if (bls->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> > +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > +					RKISP1_CIF_ISP_COMPAND_CTRL_BLS_ENABLE);
> > +		return;
> > +	}
> > +
> > +	rkisp1_compand_bls_config(params, &bls->config);
> > +
> > +	if (!(params->enabled_blocks &
> > +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS)))
> > +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > +				      RKISP1_CIF_ISP_COMPAND_CTRL_BLS_ENABLE);
> > +}
> > +
> > +static void rkisp1_ext_params_compand_expand(struct rkisp1_params *params,
> > +					     const union rkisp1_ext_params_config *block)
> > +{
> > +	const struct rkisp1_ext_params_compand_curve_config *curve =
> > +		&block->compand_curve;
> > +
> > +	if (curve->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> > +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > +					RKISP1_CIF_ISP_COMPAND_CTRL_EXPAND_ENABLE);
> > +		return;
> > +	}
> > +
> > +	rkisp1_compand_expand_config(params, &curve->config);
> > +
> > +	if (!(params->enabled_blocks &
> > +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND)))
> > +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > +				      RKISP1_CIF_ISP_COMPAND_CTRL_EXPAND_ENABLE);
> > +}
> > +
> > +static void rkisp1_ext_params_compand_compress(struct rkisp1_params *params,
> > +					       const union rkisp1_ext_params_config *block)
> > +{
> > +	const struct rkisp1_ext_params_compand_curve_config *curve =
> > +		&block->compand_curve;
> > +
> > +	if (curve->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> > +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > +					RKISP1_CIF_ISP_COMPAND_CTRL_COMPRESS_ENABLE);
> > +		return;
> > +	}
> > +
> > +	rkisp1_compand_compress_config(params, &curve->config);
> > +
> > +	if (!(params->enabled_blocks &
> > +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS)))
> > +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > +				      RKISP1_CIF_ISP_COMPAND_CTRL_COMPRESS_ENABLE);
> > +}
> > +
> >  typedef void (*rkisp1_block_handler)(struct rkisp1_params *params,
> >  			     const union rkisp1_ext_params_config *config);
> >
> > @@ -1939,6 +2087,24 @@ static const struct rkisp1_ext_params_handler {
> >  		.handler	= rkisp1_ext_params_afcm,
> >  		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> >  	},
> > +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS] = {
> > +		.size		= sizeof(struct rkisp1_ext_params_compand_bls_config),
> > +		.handler	= rkisp1_ext_params_compand_bls,
> > +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> > +		.features	= RKISP1_FEATURE_COMPAND,
> > +	},
> > +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND] = {
> > +		.size		= sizeof(struct rkisp1_ext_params_compand_curve_config),
> > +		.handler	= rkisp1_ext_params_compand_expand,
> > +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> > +		.features	= RKISP1_FEATURE_COMPAND,
> > +	},
> > +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS] = {
> > +		.size		= sizeof(struct rkisp1_ext_params_compand_curve_config),
> > +		.handler	= rkisp1_ext_params_compand_compress,
> > +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> > +		.features	= RKISP1_FEATURE_COMPAND,
> > +	},
> >  };
> >
> >  static void rkisp1_ext_params_config(struct rkisp1_params *params,
> > diff --git a/include/uapi/linux/rkisp1-config.h b/include/uapi/linux/rkisp1-config.h
> > index 00b09c92cca7..dd962df53af5 100644
> > --- a/include/uapi/linux/rkisp1-config.h
> > +++ b/include/uapi/linux/rkisp1-config.h
> > @@ -164,6 +164,11 @@
> >  #define RKISP1_CIF_ISP_DPF_MAX_NLF_COEFFS      17
> >  #define RKISP1_CIF_ISP_DPF_MAX_SPATIAL_COEFFS  6
> >
> > +/*
> > + * Compand
> > + */
> > +#define RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES	64
> > +
> >  /*
> >   * Measurement types
> >   */
> > @@ -851,6 +856,39 @@ struct rkisp1_params_cfg {
> >  	struct rkisp1_cif_isp_isp_other_cfg others;
> >  };
> >
> > +/**
> > + * struct rkisp1_cif_isp_compand_bls_config - Rockchip ISP1 Companding parameters (BLS)
> > + * @r: Fixed subtraction value for Bayer pattern R
> > + * @gr: Fixed subtraction value for Bayer pattern Gr
> > + * @gb: Fixed subtraction value for Bayer pattern Gb
> > + * @b: Fixed subtraction value for Bayer pattern B
> > + *
> > + * The values will be subtracted from the sensor values. Note that unlike the
> > + * dedicated BLS block, the BLS values in the compander are 20-bit unsigned.
> 
> I presume it's not worth mentioning this feature is only supported on
> specific platforms, right ?

We could, but we don't do so for the BLS block. I don't mind either way.
I think it's fairly clear from the driver code, and I would expect
people who want to use this driver to have to read the driver code
anyway.

> > + */
> > +struct rkisp1_cif_isp_compand_bls_config {
> > +	__u32 r;
> > +	__u32 gr;
> > +	__u32 gb;
> > +	__u32 b;
> > +};
> > +
> > +/**
> > + * struct rkisp1_cif_isp_compand_curve_config - Rockchip ISP1 Companding
> > + * parameters (expand and compression curves)
> 
> Here and below: multi-line comments are aligned differently in the
> rest of the file

We have a mix of all kinds of alignment styles :-( If someone wants to
clean things up, I'll ack a patch.

> * struct rkisp1_cif_isp_compand_curve_config - Rockchip ISP1 Companding
> *                                              parameters (expand and compression curves)

It would need to be

 * struct rkisp0_cif_isp_compand_curve_config - Rockchip ISP1 Companding
 *                                              parameters (expand and
 *                                              compression curves)

which starts looking ridiculous :-)

> > + * @px: Compand curve x-values. Each value stores the distance from the
> > + *      previous x-value, expressed as log2 of the distance on 5 bits.
> > + * @x: Compand curve x-values. The functionality of these parameters are
> > + *     unknown to do a lack of hardware documentation, but these are left here
> 
> s/unknown to/unknown due to/
> 
> > + *     for future compatibility purposes.
> 
> Also, the documentation of struct members in the existing code doesn't
> use '.' at the end (not totally true, some do, so up to you)

I've added one because it's a multi-sentence comment.

> > + * @y: Compand curve y-values
> > + */
> > +struct rkisp1_cif_isp_compand_curve_config {
> > +	__u8 px[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> > +	__u32 x[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> > +	__u32 y[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> > +};
> > +
> >  /*---------- PART2: Measurement Statistics ------------*/
> >
> >  /**
> > @@ -1018,6 +1056,9 @@ struct rkisp1_stat_buffer {
> >   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_HST_MEAS: Histogram statistics
> >   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_AEC_MEAS: Auto exposure statistics
> >   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_AFC_MEAS: Auto-focus statistics
> > + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS: BLS in the compand block
> > + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND: Companding expand curve
> > + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS: Compandding compress curve
> 
> s/Compandding/Companding/
> 
> >   */
> >  enum rkisp1_ext_params_block_type {
> >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_BLS,
> > @@ -1037,6 +1078,9 @@ enum rkisp1_ext_params_block_type {
> >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_HST_MEAS,
> >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_AEC_MEAS,
> >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_AFC_MEAS,
> > +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS,
> > +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND,
> > +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS,
> >  };
> >
> >  /**
> > @@ -1384,6 +1428,42 @@ struct rkisp1_ext_params_afc_config {
> >  	struct rkisp1_cif_isp_afc_config config;
> >  } __attribute__((aligned(8)));
> >
> > +/**
> > + * struct rkisp1_ext_params_compand_bls_config - RkISP1 extensible params
> > + * Compand BLS config
> 
> Here and in other places 'Compand' is spelled with capital 'C'. Is it
> intentional ?

I think Paul matched the documentation of other blocks, that write e.g.
'Histogram'.

> > + *
> > + * RkISP1 extensible parameters Companding configuration block (black level
> > + * subtraction). Identified by :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS`.
> > + *
> > + * @header: The RkISP1 extensible parameters header, see
> > + *	    :c:type:`rkisp1_ext_params_block_header`
> > + * @config: Companding BLS configuration, see
> > + *	    :c:type:`rkisp1_cif_isp_compand_bls_config`
> > + */
> > +struct rkisp1_ext_params_compand_bls_config {
> > +	struct rkisp1_ext_params_block_header header;
> > +	struct rkisp1_cif_isp_compand_bls_config config;
> > +} __attribute__((aligned(8)));
> > +
> > +/**
> > + * struct rkisp1_ext_params_compand_curve_config - RkISP1 extensible params
> > + * Compand curve config
> > + *
> > + * RkISP1 extensible parameters Companding configuration block (expand and
> > + * compression curves). Identified by
> > + * :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND`or
> > + * :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS`.
> > + *
> > + * @header: The RkISP1 extensible parameters header, see
> > + *	    :c:type:`rkisp1_ext_params_block_header`
> > + * @config: Companding curve configuration, see
> > + *	    :c:type:`rkisp1_cif_isp_compand_curve_config`
> > + */
> > +struct rkisp1_ext_params_compand_curve_config {
> > +	struct rkisp1_ext_params_block_header header;
> > +	struct rkisp1_cif_isp_compand_curve_config config;
> > +} __attribute__((aligned(8)));
> > +
> >  #define RKISP1_EXT_PARAMS_MAX_SIZE					\
> >  	(sizeof(struct rkisp1_ext_params_bls_config)			+\
> >  	sizeof(struct rkisp1_ext_params_dpcc_config)			+\
> > @@ -1401,7 +1481,10 @@ struct rkisp1_ext_params_afc_config {
> >  	sizeof(struct rkisp1_ext_params_awb_meas_config)		+\
> >  	sizeof(struct rkisp1_ext_params_hst_config)			+\
> >  	sizeof(struct rkisp1_ext_params_aec_config)			+\
> > -	sizeof(struct rkisp1_ext_params_afc_config))
> > +	sizeof(struct rkisp1_ext_params_afc_config)			+\
> > +	sizeof(struct rkisp1_ext_params_compand_bls_config)		+\
> > +	sizeof(struct rkisp1_ext_params_compand_curve_config)		+\
> > +	sizeof(struct rkisp1_ext_params_compand_curve_config))
> 
> Do we need a comment to say why there are two entries of the same
> type or not ?

I'll add one.

> >
> >  /**
> >   * enum rksip1_ext_param_buffer_version - RkISP1 extensible parameters version

Hi Laurent

On Thu, Jul 04, 2024 at 03:53:29PM GMT, Laurent Pinchart wrote:
> On Thu, Jul 04, 2024 at 12:40:42PM +0200, Jacopo Mondi wrote:
> > Hi Laurent
> > On Thu, Jul 04, 2024 at 01:25:33AM GMT, Laurent Pinchart wrote:
> > > From: Paul Elder <paul.elder@ideasonboard.com>
> > >
> > > Add support to the rkisp1 driver for the companding block that exists on
> > > the i.MX8MP version of the ISP. This requires usage of the new
> > > extensible parameters format, and showcases how the format allows for
> > > extensions without breaking backward compatibility.
> > >
> > > Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > ---
> > > Changes since v0:
> > >
> > > - Drop RKISP1_EXT_PARAM_BUFFER_V2
> > > - Use common structure for compression and expansion curves
> > > - Rename config fields in rkisp1_ext_params_*_config to just config
> > > - Mention block type in structures documentation
> > > - Constify arguments
> > > - Replace __uxx types with uxx
> > > - Use rkisp1_bls_swap_regs() helper in rkisp1_compand_bls_config()
> > > - Use generic feature handling mechanism
> > > ---
> > >  .../platform/rockchip/rkisp1/rkisp1-params.c  | 166 ++++++++++++++++++
> > >  include/uapi/linux/rkisp1-config.h            |  85 ++++++++-
> > >  2 files changed, 250 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> > > index bac9d4972493..5865d53be9c8 100644
> > > --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> > > +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> > > @@ -57,6 +57,8 @@ union rkisp1_ext_params_config {
> > >  	struct rkisp1_ext_params_hst_config hst;
> > >  	struct rkisp1_ext_params_aec_config aec;
> > >  	struct rkisp1_ext_params_afc_config afc;
> > > +	struct rkisp1_ext_params_compand_bls_config compand_bls;
> > > +	struct rkisp1_ext_params_compand_curve_config compand_curve;
> > >  };
> > >
> > >  enum rkisp1_params_formats {
> > > @@ -1258,6 +1260,92 @@ rkisp1_dpf_strength_config(struct rkisp1_params *params,
> > >  	rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_DPF_STRENGTH_R, arg->r);
> > >  }
> > >
> > > +static void rkisp1_compand_write_px_curve(struct rkisp1_params *params,
> > > +					  unsigned int addr, const u8 *px_curve)
> > > +{
> > > +	size_t i, j;
> > > +	u32 val;
> > > +
> > > +	/*
> > > +	 * The compand curve is specified as a piecewise linear function with
> > > +	 * 64 points. X coordinates are stored as a log2 of the displacement
> > > +	 * from the previous point, in 5 bits, with 6 values per register. The
> > > +	 * last register stores 4 values.
> > > +	 */
> > > +	for (i = 0; i < 10; i++) {
> > > +		val = 0;
> > > +		for (j = 0; j < 6; j++)
> >
> > This loops up to (9 * 6 + 5 = 59) and writes registers up to PX9
> > This should probably be i < 11 or <= 10 as the companding PX curve has
> > 64 points and 10 registers.
> >
> > Also, to make sure, I would define the number of PX() registers
> > entries instead of using the crude '10' and '6' values
> >
> > > +			val |= ((px_curve[i * 6 + j] & 0x1f) << (j * 5));
> >
> > Can't you just assign val without initializing it to 0 first and
> > or-ing it later ?
>
> I'm not sure to see what you mean here.

Nothing, I mis-read the code :)


>
> > Also, once you make the external loop go up to 11, the last two
> > iterations will out-of-bound access px[64] and px[65] (px is declared
> > of size "RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES 64").
> >
> > So this probably needs a check:
> >
> >                 if (i == 10 && j > 3)
> >                         break;
> >
> > before accessing px_curve[], or maybe declare the for loop as
> >
> > 		for (j = 0; j < (i == 10 ? 4 : 6); j++)
> >
> > > +		rkisp1_write(params->rkisp1, addr + (i * 4), val);
> >
> > Then the parameteric macros
> > RKISP1_CIF_ISP_COMPAND_EXPAND_PX_N(n)
> > RKISP1_CIF_ISP_COMPAND_COMPRESS_PX_N(n)
> >
> > are unused if not for the base address. Should you remove them and
> > only declare the base address value ?
>
> I think it's useful to document what's available in terms of register
> macros, even if not everything is used.
>
> > > +	}
> > > +
> > > +	val = 0;
> > > +	for (j = 0; j < 4; j++)
> > > +		val |= ((px_curve[60 + j] & 0x1f) << (j * 5));
> >
> > ...
> >
> > ok, I should maybe read the whole function before commenting. I left
> > the above comments there in case you want to unify the loop.
>
> I'll try to rework the code.
>
> > > +	rkisp1_write(params->rkisp1, addr + (i * 4), val);
> > > +}
> > > +
> > > +static void
> > > +rkisp1_compand_write_curve_mem(struct rkisp1_params *params,
> > > +			       unsigned int reg_addr, unsigned int reg_data,
> > > +			       size_t num_samples, const u32 *curve)
> >
> > isn't the number of samples fixed to
> > RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES ?
>
> A previous version of the patch had two macros for the expand and
> compress curves. Now that it's unified, I can drop the argument.
>
> > > +{
> > > +	size_t i;
> >
> > why a size and not an unsigned int ?
>
> The patch is originally from Paul, I don't know. I'll switch to unsigned
> int as size_t is 64-bit on 64-bit platforms, which is overkill.
>
> > > +
> > > +	for (i = 0; i < num_samples; i++) {
> > > +		rkisp1_write(params->rkisp1, reg_addr, i);
> > > +		rkisp1_write(params->rkisp1, reg_data, curve[i]);
> > > +	}
> > > +}
> > > +
> > > +static void
> > > +rkisp1_compand_bls_config(struct rkisp1_params *params,
> > > +			  const struct rkisp1_cif_isp_compand_bls_config *arg)
> > > +{
> > > +	static const u32 regs[] = {
> > > +		RKISP1_CIF_ISP_COMPAND_BLS_A_FIXED,
> > > +		RKISP1_CIF_ISP_COMPAND_BLS_B_FIXED,
> > > +		RKISP1_CIF_ISP_COMPAND_BLS_C_FIXED,
> > > +		RKISP1_CIF_ISP_COMPAND_BLS_D_FIXED,
> > > +	};
> > > +	u32 swapped[4];
> > > +
> > > +	rkisp1_bls_swap_regs(params->raw_type, regs, swapped);
> > > +
> > > +	rkisp1_write(params->rkisp1, swapped[0], arg->r);
> > > +	rkisp1_write(params->rkisp1, swapped[1], arg->gr);
> > > +	rkisp1_write(params->rkisp1, swapped[2], arg->gb);
> > > +	rkisp1_write(params->rkisp1, swapped[3], arg->b);
> > > +}
> > > +
> > > +static void
> > > +rkisp1_compand_expand_config(struct rkisp1_params *params,
> > > +			     const struct rkisp1_cif_isp_compand_curve_config *arg)
> > > +{
> > > +	rkisp1_compand_write_px_curve(params, RKISP1_CIF_ISP_COMPAND_EXPAND_PX_N(0),
> > > +				      arg->px);
> > > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_EXPAND_Y_ADDR,
> > > +				       RKISP1_CIF_ISP_COMPAND_EXPAND_Y_WRITE_DATA,
> > > +				       ARRAY_SIZE(arg->y), arg->y);
> > > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_EXPAND_X_ADDR,
> > > +				       RKISP1_CIF_ISP_COMPAND_EXPAND_X_WRITE_DATA,
> > > +				       ARRAY_SIZE(arg->x), arg->x);
> >
> > As the header reports
> >
> >  * @x: Compand curve x-values. The functionality of these parameters are
> >  *     unknown to do a lack of hardware documentation, but these are left here
> >
> >  is it safe to write them ?
>
> Yes. They don't seem to have an effect, but they're written.
>
> > > +}
> > > +
> > > +static void
> > > +rkisp1_compand_compress_config(struct rkisp1_params *params,
> > > +			       const struct rkisp1_cif_isp_compand_curve_config *arg)
> > > +{
> > > +	rkisp1_compand_write_px_curve(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_PX_N(0),
> > > +				      arg->px);
> > > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_Y_ADDR,
> > > +				       RKISP1_CIF_ISP_COMPAND_COMPRESS_Y_WRITE_DATA,
> > > +				       ARRAY_SIZE(arg->y), arg->y);
> > > +	rkisp1_compand_write_curve_mem(params, RKISP1_CIF_ISP_COMPAND_COMPRESS_X_ADDR,
> > > +				       RKISP1_CIF_ISP_COMPAND_COMPRESS_X_WRITE_DATA,
> > > +				       ARRAY_SIZE(arg->x), arg->x);
> > > +}
> > > +
> > >  static void
> > >  rkisp1_isp_isr_other_config(struct rkisp1_params *params,
> > >  			    const struct rkisp1_params_cfg *new_params)
> > > @@ -1844,6 +1932,66 @@ rkisp1_ext_params_afcm(struct rkisp1_params *params,
> > >  				      RKISP1_CIF_ISP_AFM_ENA);
> > >  }
> > >
> > > +static void rkisp1_ext_params_compand_bls(struct rkisp1_params *params,
> > +					  const union rkisp1_ext_params_config *block)
> >
> > nit: I presume going over 80-cols here is intentional
>
> I think so :-)
>
> > > +{
> > > +	const struct rkisp1_ext_params_compand_bls_config *bls =
> > > +		&block->compand_bls;
> > > +
> > > +	if (bls->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> > > +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > > +					RKISP1_CIF_ISP_COMPAND_CTRL_BLS_ENABLE);
> > > +		return;
> > > +	}
> > > +
> > > +	rkisp1_compand_bls_config(params, &bls->config);
> > > +
> > > +	if (!(params->enabled_blocks &
> > > +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS)))
> > > +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > > +				      RKISP1_CIF_ISP_COMPAND_CTRL_BLS_ENABLE);
> > > +}
> > > +
> > > +static void rkisp1_ext_params_compand_expand(struct rkisp1_params *params,
> > > +					     const union rkisp1_ext_params_config *block)
> > > +{
> > > +	const struct rkisp1_ext_params_compand_curve_config *curve =
> > > +		&block->compand_curve;
> > > +
> > > +	if (curve->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> > > +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > > +					RKISP1_CIF_ISP_COMPAND_CTRL_EXPAND_ENABLE);
> > > +		return;
> > > +	}
> > > +
> > > +	rkisp1_compand_expand_config(params, &curve->config);
> > > +
> > > +	if (!(params->enabled_blocks &
> > > +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND)))
> > > +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > > +				      RKISP1_CIF_ISP_COMPAND_CTRL_EXPAND_ENABLE);
> > > +}
> > > +
> > > +static void rkisp1_ext_params_compand_compress(struct rkisp1_params *params,
> > > +					       const union rkisp1_ext_params_config *block)
> > > +{
> > > +	const struct rkisp1_ext_params_compand_curve_config *curve =
> > > +		&block->compand_curve;
> > > +
> > > +	if (curve->header.enable == RKISP1_EXT_PARAMS_BLOCK_DISABLE) {
> > > +		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > > +					RKISP1_CIF_ISP_COMPAND_CTRL_COMPRESS_ENABLE);
> > > +		return;
> > > +	}
> > > +
> > > +	rkisp1_compand_compress_config(params, &curve->config);
> > > +
> > > +	if (!(params->enabled_blocks &
> > > +	      BIT(RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS)))
> > > +		rkisp1_param_set_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
> > > +				      RKISP1_CIF_ISP_COMPAND_CTRL_COMPRESS_ENABLE);
> > > +}
> > > +
> > >  typedef void (*rkisp1_block_handler)(struct rkisp1_params *params,
> > >  			     const union rkisp1_ext_params_config *config);
> > >
> > > @@ -1939,6 +2087,24 @@ static const struct rkisp1_ext_params_handler {
> > >  		.handler	= rkisp1_ext_params_afcm,
> > >  		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> > >  	},
> > > +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS] = {
> > > +		.size		= sizeof(struct rkisp1_ext_params_compand_bls_config),
> > > +		.handler	= rkisp1_ext_params_compand_bls,
> > > +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> > > +		.features	= RKISP1_FEATURE_COMPAND,
> > > +	},
> > > +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND] = {
> > > +		.size		= sizeof(struct rkisp1_ext_params_compand_curve_config),
> > > +		.handler	= rkisp1_ext_params_compand_expand,
> > > +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> > > +		.features	= RKISP1_FEATURE_COMPAND,
> > > +	},
> > > +	[RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS] = {
> > > +		.size		= sizeof(struct rkisp1_ext_params_compand_curve_config),
> > > +		.handler	= rkisp1_ext_params_compand_compress,
> > > +		.group		= RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> > > +		.features	= RKISP1_FEATURE_COMPAND,
> > > +	},
> > >  };
> > >
> > >  static void rkisp1_ext_params_config(struct rkisp1_params *params,
> > > diff --git a/include/uapi/linux/rkisp1-config.h b/include/uapi/linux/rkisp1-config.h
> > > index 00b09c92cca7..dd962df53af5 100644
> > > --- a/include/uapi/linux/rkisp1-config.h
> > > +++ b/include/uapi/linux/rkisp1-config.h
> > > @@ -164,6 +164,11 @@
> > >  #define RKISP1_CIF_ISP_DPF_MAX_NLF_COEFFS      17
> > >  #define RKISP1_CIF_ISP_DPF_MAX_SPATIAL_COEFFS  6
> > >
> > > +/*
> > > + * Compand
> > > + */
> > > +#define RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES	64
> > > +
> > >  /*
> > >   * Measurement types
> > >   */
> > > @@ -851,6 +856,39 @@ struct rkisp1_params_cfg {
> > >  	struct rkisp1_cif_isp_isp_other_cfg others;
> > >  };
> > >
> > > +/**
> > > + * struct rkisp1_cif_isp_compand_bls_config - Rockchip ISP1 Companding parameters (BLS)
> > > + * @r: Fixed subtraction value for Bayer pattern R
> > > + * @gr: Fixed subtraction value for Bayer pattern Gr
> > > + * @gb: Fixed subtraction value for Bayer pattern Gb
> > > + * @b: Fixed subtraction value for Bayer pattern B
> > > + *
> > > + * The values will be subtracted from the sensor values. Note that unlike the
> > > + * dedicated BLS block, the BLS values in the compander are 20-bit unsigned.
> >
> > I presume it's not worth mentioning this feature is only supported on
> > specific platforms, right ?
>
> We could, but we don't do so for the BLS block. I don't mind either way.
> I think it's fairly clear from the driver code, and I would expect
> people who want to use this driver to have to read the driver code
> anyway.
>

Yeah, and we should also mention what platforms all other blocks apply
to. Don't bother.

> > > + */
> > > +struct rkisp1_cif_isp_compand_bls_config {
> > > +	__u32 r;
> > > +	__u32 gr;
> > > +	__u32 gb;
> > > +	__u32 b;
> > > +};
> > > +
> > > +/**
> > > + * struct rkisp1_cif_isp_compand_curve_config - Rockchip ISP1 Companding
> > > + * parameters (expand and compression curves)
> >
> > Here and below: multi-line comments are aligned differently in the
> > rest of the file
>
> We have a mix of all kinds of alignment styles :-( If someone wants to
> clean things up, I'll ack a patch.
>
> > * struct rkisp1_cif_isp_compand_curve_config - Rockchip ISP1 Companding
> > *                                              parameters (expand and compression curves)
>
> It would need to be
>
>  * struct rkisp0_cif_isp_compand_curve_config - Rockchip ISP1 Companding
>  *                                              parameters (expand and
>  *                                              compression curves)
>
> which starts looking ridiculous :-)
>

I can't disagree

> > > + * @px: Compand curve x-values. Each value stores the distance from the
> > > + *      previous x-value, expressed as log2 of the distance on 5 bits.
> > > + * @x: Compand curve x-values. The functionality of these parameters are
> > > + *     unknown to do a lack of hardware documentation, but these are left here
> >
> > s/unknown to/unknown due to/
> >
> > > + *     for future compatibility purposes.
> >
> > Also, the documentation of struct members in the existing code doesn't
> > use '.' at the end (not totally true, some do, so up to you)
>
> I've added one because it's a multi-sentence comment.
>
> > > + * @y: Compand curve y-values
> > > + */
> > > +struct rkisp1_cif_isp_compand_curve_config {
> > > +	__u8 px[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> > > +	__u32 x[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> > > +	__u32 y[RKISP1_CIF_ISP_COMPAND_MAX_SAMPLES];
> > > +};
> > > +
> > >  /*---------- PART2: Measurement Statistics ------------*/
> > >
> > >  /**
> > > @@ -1018,6 +1056,9 @@ struct rkisp1_stat_buffer {
> > >   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_HST_MEAS: Histogram statistics
> > >   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_AEC_MEAS: Auto exposure statistics
> > >   * @RKISP1_EXT_PARAMS_BLOCK_TYPE_AFC_MEAS: Auto-focus statistics
> > > + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS: BLS in the compand block
> > > + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND: Companding expand curve
> > > + * @RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS: Compandding compress curve
> >
> > s/Compandding/Companding/
> >
> > >   */
> > >  enum rkisp1_ext_params_block_type {
> > >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_BLS,
> > > @@ -1037,6 +1078,9 @@ enum rkisp1_ext_params_block_type {
> > >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_HST_MEAS,
> > >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_AEC_MEAS,
> > >  	RKISP1_EXT_PARAMS_BLOCK_TYPE_AFC_MEAS,
> > > +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS,
> > > +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND,
> > > +	RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS,
> > >  };
> > >
> > >  /**
> > > @@ -1384,6 +1428,42 @@ struct rkisp1_ext_params_afc_config {
> > >  	struct rkisp1_cif_isp_afc_config config;
> > >  } __attribute__((aligned(8)));
> > >
> > > +/**
> > > + * struct rkisp1_ext_params_compand_bls_config - RkISP1 extensible params
> > > + * Compand BLS config
> >
> > Here and in other places 'Compand' is spelled with capital 'C'. Is it
> > intentional ?
>
> I think Paul matched the documentation of other blocks, that write e.g.
> 'Histogram'.
>
> > > + *
> > > + * RkISP1 extensible parameters Companding configuration block (black level
> > > + * subtraction). Identified by :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_BLS`.
> > > + *
> > > + * @header: The RkISP1 extensible parameters header, see
> > > + *	    :c:type:`rkisp1_ext_params_block_header`
> > > + * @config: Companding BLS configuration, see
> > > + *	    :c:type:`rkisp1_cif_isp_compand_bls_config`
> > > + */
> > > +struct rkisp1_ext_params_compand_bls_config {
> > > +	struct rkisp1_ext_params_block_header header;
> > > +	struct rkisp1_cif_isp_compand_bls_config config;
> > > +} __attribute__((aligned(8)));
> > > +
> > > +/**
> > > + * struct rkisp1_ext_params_compand_curve_config - RkISP1 extensible params
> > > + * Compand curve config
> > > + *
> > > + * RkISP1 extensible parameters Companding configuration block (expand and
> > > + * compression curves). Identified by
> > > + * :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND`or
> > > + * :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS`.
> > > + *
> > > + * @header: The RkISP1 extensible parameters header, see
> > > + *	    :c:type:`rkisp1_ext_params_block_header`
> > > + * @config: Companding curve configuration, see
> > > + *	    :c:type:`rkisp1_cif_isp_compand_curve_config`
> > > + */
> > > +struct rkisp1_ext_params_compand_curve_config {
> > > +	struct rkisp1_ext_params_block_header header;
> > > +	struct rkisp1_cif_isp_compand_curve_config config;
> > > +} __attribute__((aligned(8)));
> > > +
> > >  #define RKISP1_EXT_PARAMS_MAX_SIZE					\
> > >  	(sizeof(struct rkisp1_ext_params_bls_config)			+\
> > >  	sizeof(struct rkisp1_ext_params_dpcc_config)			+\
> > > @@ -1401,7 +1481,10 @@ struct rkisp1_ext_params_afc_config {
> > >  	sizeof(struct rkisp1_ext_params_awb_meas_config)		+\
> > >  	sizeof(struct rkisp1_ext_params_hst_config)			+\
> > >  	sizeof(struct rkisp1_ext_params_aec_config)			+\
> > > -	sizeof(struct rkisp1_ext_params_afc_config))
> > > +	sizeof(struct rkisp1_ext_params_afc_config)			+\
> > > +	sizeof(struct rkisp1_ext_params_compand_bls_config)		+\
> > > +	sizeof(struct rkisp1_ext_params_compand_curve_config)		+\
> > > +	sizeof(struct rkisp1_ext_params_compand_curve_config))
> >
> > Do we need a comment to say why there are two entries of the same
> > type or not ?
>
> I'll add one.
>

Thanks
  j

> > >
> > >  /**
> > >   * enum rksip1_ext_param_buffer_version - RkISP1 extensible parameters version
>
> --
> Regards,
>
> Laurent Pinchart