diff mbox series

[v3,8/9] media: i2c: ov9282: add strobe_duration v4l2 control

Message ID 20250429-ov9282-flash-strobe-v3-8-2105ce179952@linux.dev
State Superseded
Headers show
Series Add strobe/flash duration v4l2 ctrl & use it for ov9282 | expand

Commit Message

Richard Leitner April 29, 2025, 12:59 p.m. UTC 
Add V4L2_CID_FLASH_DURATION support using the "strobe_frame_span"
feature of the sensor. This is implemented by transforming the given µs
value by an interpolated formula to a "span step width" value and
writing it to register PWM_CTRL_25, PWM_CTRL_26, PWM_CTRL_27,
PWM_CTRL_28 (0x3925, 0x3926, 0x3927, 0x3928).

The maximum control value is set to the period of the current default
framerate.

All register values are based on the OV9281 datasheet v1.53 (jan 2019)
and tested using an ov9281 VisionComponents module.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/i2c/ov9282.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

Comments

Sakari Ailus May 1, 2025, 10:22 p.m. UTC | #1 
Hi Richard,

On Wed, Apr 30, 2025 at 11:09:30AM +0200, Richard Leitner wrote:
> Hi Sakari,
> 
> thanks for the review!

You're welcome.

> > > +	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> > 
> > Should the number of controls in the handler be updated?
> 
> What do you mean by "number of controls in the handler" exactly? Which
> handler?

A number of buckets allocated in control handler's initialisation is based
on the number of controls given to the init function. You should update
that number when adding controls.
Richard Leitner May 6, 2025, 9:37 a.m. UTC | #2 
On Thu, May 01, 2025 at 10:22:38PM +0000, Sakari Ailus wrote:
> Hi Richard,
> 
> On Wed, Apr 30, 2025 at 11:09:30AM +0200, Richard Leitner wrote:
> > Hi Sakari,
> > 
> > thanks for the review!
> 
> You're welcome.
> 
> > > > +	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> > > 
> > > Should the number of controls in the handler be updated?
> > 
> > What do you mean by "number of controls in the handler" exactly? Which
> > handler?
> 
> A number of buckets allocated in control handler's initialisation is based
> on the number of controls given to the init function. You should update
> that number when adding controls.

Ah, now I got it. :-)

Thanks for the clarification. Will fix that in v4 for all newly added
controls!

regards;rl

> 
> -- 
> Regards,
> 
> Sakari Ailus
diff mbox series

Patch

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index 35edbe1e0efb61a0e03da0ed817c4c4ec0ae9c35..5ddbfc51586111fbd2e17b739fb3d28bfb0aee1e 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -97,6 +97,10 @@ 
 #define OV9282_REG_MIPI_CTRL00	0x4800
 #define OV9282_GATED_CLOCK	BIT(5)
 
+/* Flash/Strobe control registers */
+#define OV9282_REG_FLASH_DURATION	0x3925
+#define OV9282_FLASH_DURATION_DEFAULT	0x0000001A
+
 /* Input clock rate */
 #define OV9282_INCLK_RATE	24000000
 
@@ -687,6 +691,24 @@  static int ov9282_set_ctrl_flash_led_mode(struct ov9282 *ov9282, int mode)
 				current_val);
 }
 
+static int ov9282_set_ctrl_flash_duration(struct ov9282 *ov9282, int value)
+{
+	/* Calculate "strobe_frame_span" increments from a given value (µs).
+	 * This is quite tricky as "The step width of shift and span is
+	 * programmable under system clock domain.", but it's not documented
+	 * how to program this step width (at least in the datasheet available
+	 * to the author at time of writing).
+	 * The formula below is interpolated from different modes/framerates
+	 * and should work quite well for most settings.
+	 */
+	u32 val = value * 192 / (ov9282->cur_mode->width + ov9282->hblank_ctrl->val);
+
+	ov9282_write_reg(ov9282, OV9282_REG_FLASH_DURATION, 1, (val >> 24) & 0xff);
+	ov9282_write_reg(ov9282, OV9282_REG_FLASH_DURATION + 1, 1, (val >> 16) & 0xff);
+	ov9282_write_reg(ov9282, OV9282_REG_FLASH_DURATION + 2, 1, (val >> 8) & 0xff);
+	return ov9282_write_reg(ov9282, OV9282_REG_FLASH_DURATION + 3, 1, val & 0xff);
+}
+
 /**
  * ov9282_set_ctrl() - Set subdevice control
  * @ctrl: pointer to v4l2_ctrl structure
@@ -756,6 +778,9 @@  static int ov9282_set_ctrl(struct v4l2_ctrl *ctrl)
 	case V4L2_CID_FLASH_LED_MODE:
 		ret = ov9282_set_ctrl_flash_led_mode(ov9282, ctrl->val);
 		break;
+	case V4L2_CID_FLASH_DURATION:
+		ret = ov9282_set_ctrl_flash_duration(ov9282, ctrl->val);
+		break;
 	default:
 		dev_err(ov9282->dev, "Invalid control %d", ctrl->id);
 		ret = -EINVAL;
@@ -1418,6 +1443,9 @@  static int ov9282_init_controls(struct ov9282 *ov9282)
 			       (1 << V4L2_FLASH_LED_MODE_TORCH),
 			       V4L2_FLASH_LED_MODE_NONE);
 
+	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
+			  0, 13900, 1, 8);
+
 	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
 	if (!ret) {
 		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */