[v2,4/4] rkvdec: Improve error handling

There are two ways decoding errors can occure. In one case, the ready
status is not set and nothing has been written into the destination,
while in the other case, the buffer is written but may contain a
certain amount of errors. In order to differentiate these, we set
the payload for the first case to 0.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
---
 drivers/staging/media/rkvdec/rkvdec.c | 31 +++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

Hi Nicolas,

Thanks a lot for the patchset. I have just some style feedback.

On Fri, Dec 23, 2022 at 02:38:06PM -0500, Nicolas Dufresne wrote:
> There are two ways decoding errors can occure. In one case, the ready
> status is not set and nothing has been written into the destination,
> while in the other case, the buffer is written but may contain a
> certain amount of errors. In order to differentiate these, we set
> the payload for the first case to 0.
> 
> Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> ---
>  drivers/staging/media/rkvdec/rkvdec.c | 31 +++++++++++++++++++++++----
>  1 file changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/media/rkvdec/rkvdec.c b/drivers/staging/media/rkvdec/rkvdec.c
> index 7e76f8b728854..11e2bbb20aea1 100644
> --- a/drivers/staging/media/rkvdec/rkvdec.c
> +++ b/drivers/staging/media/rkvdec/rkvdec.c
> @@ -27,6 +27,9 @@
>  #include "rkvdec.h"
>  #include "rkvdec-regs.h"
>  
> +static int debug;
> +module_param(debug, int, 0644);
> +
>  static int rkvdec_try_ctrl(struct v4l2_ctrl *ctrl)
>  {
>  	struct rkvdec_ctx *ctx = container_of(ctrl->handler, struct rkvdec_ctx, ctrl_hdl);
> @@ -954,14 +957,34 @@ static irqreturn_t rkvdec_irq_handler(int irq, void *priv)
>  	enum vb2_buffer_state state;
>  	u32 status;
>  
> +	ctx = v4l2_m2m_get_curr_priv(rkvdec->m2m_dev);
>  	status = readl(rkvdec->regs + RKVDEC_REG_INTERRUPT);

Maybe group the I/O together, i.e. the writel would
be right after this readl:

    writel(0, rkvdec->regs + RKVDEC_REG_INTERRUPT);

> -	state = (status & RKVDEC_RDY_STA) ?
> -		VB2_BUF_STATE_DONE : VB2_BUF_STATE_ERROR;
> +
> +	if (!(status & RKVDEC_RDY_STA)) {
> +		struct vb2_v4l2_buffer *dst_buf = NULL;
> +
> +		if (status & RKVDEC_TIMEOUT_STA)
> +			v4l2_dbg(debug, 1, &rkvdec->v4l2_dev,
> +				 "Decoder stopped due to an internal timeout.");
> +		else
> +			v4l2_dbg(debug, 1, &rkvdec->v4l2_dev,
> +				 "Decoder stopped due to an internal error.");

Unless you really want to ensure this string is greppable,
you can do something like:

v4l2_dbg(debug, 1, &rkvdec->v4l2_dev, "Decoder stopped due to an internal %s.", .... ? "error" : "timeout");

> +
> +		/*
> +		 * When this happens, the buffer is left unmodified. As it
> +		 * contains no meaningful data we mark is as empty.
> +		 */
> +		dst_buf = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
> +		vb2_set_plane_payload(&dst_buf->vb2_buf, 0, 0);

Perhaps we can avoid this vb2_set_plane_payload(&dst_buf->vb2_buf, 0, 0);
if we instead set the payload in rkvdec_job_finish_no_pm().
It would change the behavior, as we would be setting payload
only when state is _DONE, so maybe that's not what you want.

> +		state = VB2_BUF_STATE_ERROR;
> +	} else {
> +		state = VB2_BUF_STATE_DONE;
> +	}
>  
>  	writel(0, rkvdec->regs + RKVDEC_REG_INTERRUPT);
> -	ctx = v4l2_m2m_get_curr_priv(rkvdec->m2m_dev);
>  
> -	if (ctx->coded_fmt_desc->ops->check_error_info)
> +	if (ctx->coded_fmt_desc->ops->check_error_info &&
> +	    state == VB2_BUF_STATE_DONE)
>  		state = ctx->coded_fmt_desc->ops->check_error_info(ctx);
>  

How about this:

static irqreturn_t rkvdec_irq_handler(int irq, void *priv)
{
    struct rkvdec_dev *rkvdec = priv;
    struct rkvdec_ctx *ctx;
    enum vb2_buffer_state state = VB2_BUF_STATE_DONE;
    u32 status;

    ctx = v4l2_m2m_get_curr_priv(rkvdec->m2m_dev);
    status = readl(rkvdec->regs + RKVDEC_REG_INTERRUPT);
    writel(0, rkvdec->regs + RKVDEC_REG_INTERRUPT);

    if (!(status & RKVDEC_RDY_STA)) {
        ...
        state = VB2_BUF_STATE_ERROR;
    } else {
        if (ctx->coded_fmt_desc->ops->check_error_info &&
            ctx->coded_fmt_desc->ops->check_error_info(ctx))
            state = VB2_BUF_STATE_ERROR;
    }

    if (cancel_delayed_work(&rkvdec->watchdog_work))
        rkvdec_job_finish(ctx, state);

    return IRQ_HANDLED;
}

So it's clear which paths lead to VB2_BUF_STATE_ERROR.

Thanks!
Ezequiel

>  	if (cancel_delayed_work(&rkvdec->watchdog_work))
> -- 
> 2.38.1
>