[PATCH v3 0/9] Add strobe/flash duration v4l2 ctrl & use it for ov9282

[PATCH v3 0/9] Add strobe/flash duration v4l2 ctrl & use it for ov9282

[Richard Leitner]

This series adds a new v4l2 controls named "strobe duration" with id
V4L2_CID_FLASH_DURATION. This control enables setting a desired
flash/strobe length/duration in µs.

As a first user of this new control add basic flash/strobe support for
ov9282 sensors using their "hardware strobe output". The duration
calculation is only interpolated from various measurements, as no
documentation was found.

Further flash/strobe-related controls as well as a migration to v4l2-cci
helpers for ov9282 will likely be implemented in future series.

All register addresses/values are based on the OV9281 datasheet v1.53
(january 2019). This series was tested using an ov9281 VisionComponents
camera module.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
Changes in v3:
- create separate patch for leds driver changes (thanks Lee)
- Link to v2: https://lore.kernel.org/r/20250314-ov9282-flash-strobe-v2-0-14d7a281342d@linux.dev

Changes in v2:
- remove not needed controls in struct ov9282 (thanks Dave)
- Fix commit message of 3/3 regarding framerate get/set (thanks Dave)
- Add V4L2_CID_FLASH_STROBE_SOURCE impementation to ov9282
- Add new V4L2_CID_FLASH_DURATION control (as suggested by Laurent)
- Use FLASH_DURATION instead of FLASH_TIMEOUT for ov9282
- Link to v1: https://lore.kernel.org/r/20250303-ov9282-flash-strobe-v1-0-0fd57a1564ba@linux.dev

---
Richard Leitner (9):
      media: v4l: ctrls: add a control for flash/strobe duration
      leds: flash: add support for flash/stobe duration
      media: v4l2-flash: add support for flash/strobe duration
      media: v4l2-flash: fix flash_timeout comment
      Documentation: uAPI: media: add V4L2_CID_FLASH_DURATION
      media: i2c: ov9282: add output enable register definitions
      media: i2c: ov9282: add led_mode v4l2 control
      media: i2c: ov9282: add strobe_duration v4l2 control
      media: i2c: ov9282: add strobe_source v4l2 control

 .../userspace-api/media/v4l/ext-ctrls-flash.rst    |  5 ++
 drivers/leds/led-class-flash.c                     | 15 ++++
 drivers/media/i2c/ov9282.c                         | 92 +++++++++++++++++++++-
 drivers/media/v4l2-core/v4l2-ctrls-defs.c          |  1 +
 drivers/media/v4l2-core/v4l2-flash-led-class.c     | 13 +++
 include/linux/led-class-flash.h                    | 18 ++++-
 include/uapi/linux/v4l2-controls.h                 |  1 +
 7 files changed, 141 insertions(+), 4 deletions(-)
---
base-commit: ca91b9500108d4cf083a635c2e11c884d5dd20ea
change-id: 20250303-ov9282-flash-strobe-ac6bd00c9de6
prerequisite-change-id: 20250225-b4-ov9282-gain-ef1cdaba5bfd:v1
prerequisite-patch-id: 86f2582378ff7095ab65ce4bb25a143eb639e840
prerequisite-patch-id: b06eb6ec697aaf0b3155b4b2370f171d0d304ae2
prerequisite-patch-id: b123047d71bfb9b93f743bbdd6893d5a98495801

Best regards,
-- 
Richard Leitner <richard.leitner@linux.dev>

[PATCH v3 1/9] media: v4l: ctrls: add a control for flash/strobe duration

[Richard Leitner]

Add a control V4L2_CID_FLASH_DURATION to set the duration of a
flash/strobe pulse. This is different to the V4L2_CID_FLASH_TIMEOUT
control, as the timeout defines a limit after which the flash is
"forcefully" turned off again.

On the other hand the new V4L2_CID_FLASH_DURATION is the desired length
of the flash/strobe pulse.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/v4l2-core/v4l2-ctrls-defs.c | 1 +
 include/uapi/linux/v4l2-controls.h        | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
index 1ea52011247accc51d0261f56eab1cf13c0624a0..f9ed7273a9f3eafe01c31b638e1c8d9fcf5424af 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
@@ -1135,6 +1135,7 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_FLASH_FAULT:		return "Faults";
 	case V4L2_CID_FLASH_CHARGE:		return "Charge";
 	case V4L2_CID_FLASH_READY:		return "Ready to Strobe";
+	case V4L2_CID_FLASH_DURATION:		return "Strobe Duration";
 
 	/* JPEG encoder controls */
 	/* Keep the order of the 'case's the same as in v4l2-controls.h! */
diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
index 72e32814ea83dee5f1202c1249eac7cf3b85a22a..72c6bd26e2dfa23a0224e745e5cd07c9fca0c8b5 100644
--- a/include/uapi/linux/v4l2-controls.h
+++ b/include/uapi/linux/v4l2-controls.h
@@ -1180,6 +1180,7 @@ enum v4l2_flash_strobe_source {
 
 #define V4L2_CID_FLASH_CHARGE			(V4L2_CID_FLASH_CLASS_BASE + 11)
 #define V4L2_CID_FLASH_READY			(V4L2_CID_FLASH_CLASS_BASE + 12)
+#define V4L2_CID_FLASH_DURATION			(V4L2_CID_FLASH_CLASS_BASE + 13)
 
 
 /* JPEG-class control IDs */

-- 
2.47.2

[PATCH v3 2/9] leds: flash: add support for flash/stobe duration

[Richard Leitner]

Add support for the new V4L2_CID_FLASH_DURATION control to the leds
driver.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/leds/led-class-flash.c  | 15 +++++++++++++++
 include/linux/led-class-flash.h | 16 ++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
index f4e26ce84862c05092a9598e63ed301967852f13..165035a8826ca7d44a5cd265a5130a76c6e94347 100644
--- a/drivers/leds/led-class-flash.c
+++ b/drivers/leds/led-class-flash.c
@@ -440,6 +440,21 @@ int led_update_flash_brightness(struct led_classdev_flash *fled_cdev)
 }
 EXPORT_SYMBOL_GPL(led_update_flash_brightness);
 
+int led_set_flash_duration(struct led_classdev_flash *fled_cdev, u32 duration)
+{
+	struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+	struct led_flash_setting *s = &fled_cdev->duration;
+
+	s->val = duration;
+	led_clamp_align(s);
+
+	if (!(led_cdev->flags & LED_SUSPENDED))
+		return call_flash_op(fled_cdev, duration_set, s->val);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(led_set_flash_duration);
+
 MODULE_AUTHOR("Jacek Anaszewski <j.anaszewski@samsung.com>");
 MODULE_DESCRIPTION("LED Flash class interface");
 MODULE_LICENSE("GPL v2");
diff --git a/include/linux/led-class-flash.h b/include/linux/led-class-flash.h
index 36df927ec4b7dcaf9074c6ef32ac8ce83a87a79d..21ec856c36bc67decda46aa8ff1c040ffdcf1181 100644
--- a/include/linux/led-class-flash.h
+++ b/include/linux/led-class-flash.h
@@ -45,6 +45,8 @@ struct led_flash_ops {
 	int (*timeout_set)(struct led_classdev_flash *fled_cdev, u32 timeout);
 	/* get the flash LED fault */
 	int (*fault_get)(struct led_classdev_flash *fled_cdev, u32 *fault);
+	/* set flash duration */
+	int (*duration_set)(struct led_classdev_flash *fled_cdev, u32 duration);
 };
 
 /*
@@ -75,6 +77,9 @@ struct led_classdev_flash {
 	/* flash timeout value in microseconds along with its constraints */
 	struct led_flash_setting timeout;
 
+	/* flash timeout value in microseconds along with its constraints */
+	struct led_flash_setting duration;
+
 	/* LED Flash class sysfs groups */
 	const struct attribute_group *sysfs_groups[LED_FLASH_SYSFS_GROUPS_SIZE];
 };
@@ -209,4 +214,15 @@ int led_set_flash_timeout(struct led_classdev_flash *fled_cdev, u32 timeout);
  */
 int led_get_flash_fault(struct led_classdev_flash *fled_cdev, u32 *fault);
 
+/**
+ * led_set_flash_duration - set flash LED duration
+ * @fled_cdev: the flash LED to set
+ * @timeout: the flash duration to set it to
+ *
+ * Set the flash strobe duration.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+int led_set_flash_duration(struct led_classdev_flash *fled_cdev, u32 duration);
+
 #endif	/* __LINUX_FLASH_LEDS_H_INCLUDED */

-- 
2.47.2

[PATCH v3 3/9] media: v4l2-flash: add support for flash/strobe duration

[Richard Leitner]

Add support for the new V4L2_CID_FLASH_DURATION control to the v4l2
flash led class.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/v4l2-core/v4l2-flash-led-class.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
index 355595a0fefac72c2f6941a30fa430d37dbdccfe..963b549480f6eb3b9eb0d80696a764de7ffcc1a2 100644
--- a/drivers/media/v4l2-core/v4l2-flash-led-class.c
+++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
@@ -298,6 +298,12 @@ static int v4l2_flash_s_ctrl(struct v4l2_ctrl *c)
 		 * microamperes for flash intensity units.
 		 */
 		return led_set_flash_brightness(fled_cdev, c->val);
+	case V4L2_CID_FLASH_DURATION:
+		/*
+		 * No conversion is needed as LED Flash class also uses
+		 * microseconds for flash duration units.
+		 */
+		return led_set_flash_duration(fled_cdev, c->val);
 	}
 
 	return -EINVAL;
@@ -424,6 +430,13 @@ static void __fill_ctrl_init_data(struct v4l2_flash *v4l2_flash,
 		ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
 				  V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
 	}
+
+	/* Init FLASH_DURATION ctrl data */
+	if (has_flash_op(fled_cdev, timeout_set)) {
+		ctrl_init_data[FLASH_DURATION].cid = V4L2_CID_FLASH_DURATION;
+		ctrl_cfg = &ctrl_init_data[FLASH_DURATION].config;
+		__lfs_to_v4l2_ctrl_config(&fled_cdev->duration, ctrl_cfg);
+		ctrl_cfg->id = V4L2_CID_FLASH_DURATION;
 }
 
 static int v4l2_flash_init_controls(struct v4l2_flash *v4l2_flash,

-- 
2.47.2

Re: [PATCH v3 3/9] media: v4l2-flash: add support for flash/strobe duration

[Sakari Ailus]

Hi Richard,

On Tue, Apr 29, 2025 at 02:59:08PM +0200, Richard Leitner wrote:
> Add support for the new V4L2_CID_FLASH_DURATION control to the v4l2
> flash led class.
> 
> Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
> ---
>  drivers/media/v4l2-core/v4l2-flash-led-class.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
> index 355595a0fefac72c2f6941a30fa430d37dbdccfe..963b549480f6eb3b9eb0d80696a764de7ffcc1a2 100644
> --- a/drivers/media/v4l2-core/v4l2-flash-led-class.c
> +++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
> @@ -298,6 +298,12 @@ static int v4l2_flash_s_ctrl(struct v4l2_ctrl *c)
>  		 * microamperes for flash intensity units.
>  		 */
>  		return led_set_flash_brightness(fled_cdev, c->val);
> +	case V4L2_CID_FLASH_DURATION:
> +		/*
> +		 * No conversion is needed as LED Flash class also uses
> +		 * microseconds for flash duration units.
> +		 */
> +		return led_set_flash_duration(fled_cdev, c->val);
>  	}
>  
>  	return -EINVAL;
> @@ -424,6 +430,13 @@ static void __fill_ctrl_init_data(struct v4l2_flash *v4l2_flash,
>  		ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
>  				  V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
>  	}
> +
> +	/* Init FLASH_DURATION ctrl data */
> +	if (has_flash_op(fled_cdev, timeout_set)) {
> +		ctrl_init_data[FLASH_DURATION].cid = V4L2_CID_FLASH_DURATION;
> +		ctrl_cfg = &ctrl_init_data[FLASH_DURATION].config;
> +		__lfs_to_v4l2_ctrl_config(&fled_cdev->duration, ctrl_cfg);
> +		ctrl_cfg->id = V4L2_CID_FLASH_DURATION;

Has this been compile tested? :-)

>  }
>  
>  static int v4l2_flash_init_controls(struct v4l2_flash *v4l2_flash,
> 

-- 
Regards,

Sakari Ailus

Re: [PATCH v3 3/9] media: v4l2-flash: add support for flash/strobe duration

[Richard Leitner]

Hi Sakari,

thanks for your quick feedback!

On Wed, Apr 30, 2025 at 08:24:00AM +0000, Sakari Ailus wrote:
> Hi Richard,
> 
> On Tue, Apr 29, 2025 at 02:59:08PM +0200, Richard Leitner wrote:
> > Add support for the new V4L2_CID_FLASH_DURATION control to the v4l2
> > flash led class.
> > 
> > Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
> > ---
> >  drivers/media/v4l2-core/v4l2-flash-led-class.c | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
> > index 355595a0fefac72c2f6941a30fa430d37dbdccfe..963b549480f6eb3b9eb0d80696a764de7ffcc1a2 100644
> > --- a/drivers/media/v4l2-core/v4l2-flash-led-class.c
> > +++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
> > @@ -298,6 +298,12 @@ static int v4l2_flash_s_ctrl(struct v4l2_ctrl *c)
> >  		 * microamperes for flash intensity units.
> >  		 */
> >  		return led_set_flash_brightness(fled_cdev, c->val);
> > +	case V4L2_CID_FLASH_DURATION:
> > +		/*
> > +		 * No conversion is needed as LED Flash class also uses
> > +		 * microseconds for flash duration units.
> > +		 */
> > +		return led_set_flash_duration(fled_cdev, c->val);
> >  	}
> >  
> >  	return -EINVAL;
> > @@ -424,6 +430,13 @@ static void __fill_ctrl_init_data(struct v4l2_flash *v4l2_flash,
> >  		ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
> >  				  V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
> >  	}
> > +
> > +	/* Init FLASH_DURATION ctrl data */
> > +	if (has_flash_op(fled_cdev, timeout_set)) {
> > +		ctrl_init_data[FLASH_DURATION].cid = V4L2_CID_FLASH_DURATION;
> > +		ctrl_cfg = &ctrl_init_data[FLASH_DURATION].config;
> > +		__lfs_to_v4l2_ctrl_config(&fled_cdev->duration, ctrl_cfg);
> > +		ctrl_cfg->id = V4L2_CID_FLASH_DURATION;
> 
> Has this been compile tested? :-)

Oooh... Damn. That's embarrasing. SORRY! There should have been at least
another '}' in this patch.... Seems I somehow messed up my last rebase.

Will fix that in v4. Sorry again :-/

> 
> >  }
> >  
> >  static int v4l2_flash_init_controls(struct v4l2_flash *v4l2_flash,
> > 
> 
> -- 
> Regards,
> 
> Sakari Ailus

regards;rl

Re: [PATCH v3 3/9] media: v4l2-flash: add support for flash/strobe duration

[Sakari Ailus]

On Wed, Apr 30, 2025 at 10:37:48AM +0200, Richard Leitner wrote:
> > > +	/* Init FLASH_DURATION ctrl data */
> > > +	if (has_flash_op(fled_cdev, timeout_set)) {
> > > +		ctrl_init_data[FLASH_DURATION].cid = V4L2_CID_FLASH_DURATION;
> > > +		ctrl_cfg = &ctrl_init_data[FLASH_DURATION].config;
> > > +		__lfs_to_v4l2_ctrl_config(&fled_cdev->duration, ctrl_cfg);
> > > +		ctrl_cfg->id = V4L2_CID_FLASH_DURATION;
> > 
> > Has this been compile tested? :-)
> 
> Oooh... Damn. That's embarrasing. SORRY! There should have been at least
> another '}' in this patch.... Seems I somehow messed up my last rebase.
> 
> Will fix that in v4. Sorry again :-/

No worries, it happens to everyone sometimes.

-- 
Sakari Ailus

[PATCH v3 4/9] media: v4l2-flash: fix flash_timeout comment

[Richard Leitner]

The comment for the flash_timeout setter mentioned it is the "flash
duration". Fix this by changing it to "flash timeout".

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 include/linux/led-class-flash.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/led-class-flash.h b/include/linux/led-class-flash.h
index 21ec856c36bc67decda46aa8ff1c040ffdcf1181..775a96217518936633541c7a5d394502dbf04f83 100644
--- a/include/linux/led-class-flash.h
+++ b/include/linux/led-class-flash.h
@@ -197,7 +197,7 @@ int led_update_flash_brightness(struct led_classdev_flash *fled_cdev);
  * @fled_cdev: the flash LED to set
  * @timeout: the flash timeout to set it to
  *
- * Set the flash strobe duration.
+ * Set the flash strobe timeout.
  *
  * Returns: 0 on success or negative error value on failure
  */

-- 
2.47.2

[PATCH v3 5/9] Documentation: uAPI: media: add V4L2_CID_FLASH_DURATION

[Richard Leitner]

Add the new strobe_duration control to v4l uAPI documentation.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst
index d22c5efb806a183a3ad67ec3e6550b002a51659a..03a58ef94be7c870f55d5a9bb09503995dbfb402 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst
@@ -186,3 +186,8 @@ Flash Control IDs
     charged before strobing. LED flashes often require a cooldown period
     after strobe during which another strobe will not be possible. This
     is a read-only control.
+
+``V4L2_CID_FLASH_DURATION (integer)``
+    Duration the flash should be on when the flash LED is in flash mode
+    (V4L2_FLASH_LED_MODE_FLASH). The unit should be microseconds (µs)
+    if possible.

-- 
2.47.2

[PATCH v3 6/9] media: i2c: ov9282: add output enable register definitions

[Richard Leitner]

Add #define's for the output enable registers (0x3004, 0x3005, 0x3006),
also known as SC_CTRL_04, SC_CTRL_05, SC_CTRL_04. Use those register
definitions instead of the raw values in the `common_regs` struct.

All values are based on the OV9281 datasheet v1.53 (january 2019).

Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/i2c/ov9282.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index c882a021cf18852237bf9b9524d3de0c5b48cbcb..f42e0d439753e74d14e3a3592029e48f49234927 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -37,6 +37,29 @@
 #define OV9282_REG_ID		0x300a
 #define OV9282_ID		0x9281
 
+/* Output enable registers */
+#define OV9282_REG_OUTPUT_ENABLE4	0x3004
+#define OV9282_OUTPUT_ENABLE4_GPIO2	BIT(1)
+#define OV9282_OUTPUT_ENABLE4_D9	BIT(0)
+
+#define OV9282_REG_OUTPUT_ENABLE5	0x3005
+#define OV9282_OUTPUT_ENABLE5_D8	BIT(7)
+#define OV9282_OUTPUT_ENABLE5_D7	BIT(6)
+#define OV9282_OUTPUT_ENABLE5_D6	BIT(5)
+#define OV9282_OUTPUT_ENABLE5_D5	BIT(4)
+#define OV9282_OUTPUT_ENABLE5_D4	BIT(3)
+#define OV9282_OUTPUT_ENABLE5_D3	BIT(2)
+#define OV9282_OUTPUT_ENABLE5_D2	BIT(1)
+#define OV9282_OUTPUT_ENABLE5_D1	BIT(0)
+
+#define OV9282_REG_OUTPUT_ENABLE6	0x3006
+#define OV9282_OUTPUT_ENABLE6_D0	BIT(7)
+#define OV9282_OUTPUT_ENABLE6_PCLK	BIT(6)
+#define OV9282_OUTPUT_ENABLE6_HREF	BIT(5)
+#define OV9282_OUTPUT_ENABLE6_STROBE	BIT(3)
+#define OV9282_OUTPUT_ENABLE6_ILPWM	BIT(2)
+#define OV9282_OUTPUT_ENABLE6_VSYNC	BIT(1)
+
 /* Exposure control */
 #define OV9282_REG_EXPOSURE	0x3500
 #define OV9282_EXPOSURE_MIN	1
@@ -213,9 +236,9 @@ static const struct ov9282_reg common_regs[] = {
 	{0x0302, 0x32},
 	{0x030e, 0x02},
 	{0x3001, 0x00},
-	{0x3004, 0x00},
-	{0x3005, 0x00},
-	{0x3006, 0x04},
+	{OV9282_REG_OUTPUT_ENABLE4, 0x00},
+	{OV9282_REG_OUTPUT_ENABLE5, 0x00},
+	{OV9282_REG_OUTPUT_ENABLE6, OV9282_OUTPUT_ENABLE6_ILPWM},
 	{0x3011, 0x0a},
 	{0x3013, 0x18},
 	{0x301c, 0xf0},

-- 
2.47.2

[PATCH v3 7/9] media: i2c: ov9282: add led_mode v4l2 control

[Richard Leitner]

Add V4L2_CID_FLASH_LED_MODE support using the "strobe output enable"
feature of the sensor. This implements following modes:

 - V4L2_FLASH_LED_MODE_NONE, which disables the strobe output
 - V4L2_FLASH_LED_MODE_FLASH, which enables the strobe output

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

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/i2c/ov9282.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index f42e0d439753e74d14e3a3592029e48f49234927..35edbe1e0efb61a0e03da0ed817c4c4ec0ae9c35 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -670,6 +670,23 @@ static int ov9282_set_ctrl_vflip(struct ov9282 *ov9282, int value)
 				current_val);
 }
 
+static int ov9282_set_ctrl_flash_led_mode(struct ov9282 *ov9282, int mode)
+{
+	u32 current_val;
+	int ret = ov9282_read_reg(ov9282, OV9282_REG_OUTPUT_ENABLE6, 1,
+				  &current_val);
+	if (ret)
+		return ret;
+
+	if (mode == V4L2_FLASH_LED_MODE_FLASH)
+		current_val |= OV9282_OUTPUT_ENABLE6_STROBE;
+	else
+		current_val &= ~OV9282_OUTPUT_ENABLE6_STROBE;
+
+	return ov9282_write_reg(ov9282, OV9282_REG_OUTPUT_ENABLE6, 1,
+				current_val);
+}
+
 /**
  * ov9282_set_ctrl() - Set subdevice control
  * @ctrl: pointer to v4l2_ctrl structure
@@ -736,6 +753,9 @@ static int ov9282_set_ctrl(struct v4l2_ctrl *ctrl)
 		ret = ov9282_write_reg(ov9282, OV9282_REG_TIMING_HTS, 2,
 				       (ctrl->val + ov9282->cur_mode->width) >> 1);
 		break;
+	case V4L2_CID_FLASH_LED_MODE:
+		ret = ov9282_set_ctrl_flash_led_mode(ov9282, ctrl->val);
+		break;
 	default:
 		dev_err(ov9282->dev, "Invalid control %d", ctrl->id);
 		ret = -EINVAL;
@@ -1391,6 +1411,13 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
 						OV9282_TIMING_HTS_MAX - mode->width,
 						1, hblank_min);
 
+	/* Flash/Strobe controls */
+	v4l2_ctrl_new_std_menu(ctrl_hdlr, &ov9282_ctrl_ops,
+			       V4L2_CID_FLASH_LED_MODE,
+			       V4L2_FLASH_LED_MODE_TORCH,
+			       (1 << V4L2_FLASH_LED_MODE_TORCH),
+			       V4L2_FLASH_LED_MODE_NONE);
+
 	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
 	if (!ret) {
 		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */

-- 
2.47.2

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

[Richard Leitner]

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(+)

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 */

-- 
2.47.2

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

[Sakari Ailus]

Hi Richard,

On Tue, Apr 29, 2025 at 02:59:13PM +0200, Richard Leitner wrote:
> 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(+)
> 
> 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).

/*
 * Multi-line
 * comment.
 */

> +	 * 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);

The granularity of the hardware supported values is lower than that of the
control. Could you add try_ctrl op to provide the actual value back to the
user space?

> +}
> +
>  /**
>   * 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,

Should the number of controls in the handler be updated?

> +			  0, 13900, 1, 8);
> +
>  	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
>  	if (!ret) {
>  		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */
> 

-- 
Regards,

Sakari Ailus

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

[Richard Leitner]

Hi Sakari,

thanks for the review!

On Wed, Apr 30, 2025 at 08:27:39AM +0000, Sakari Ailus wrote:
> Hi Richard,
> 
> On Tue, Apr 29, 2025 at 02:59:13PM +0200, Richard Leitner wrote:
> > 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(+)
> > 
> > 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).
> 
> /*
>  * Multi-line
>  * comment.
>  */

sure. will adapt that in v4.

> 
> > +	 * 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);
> 
> The granularity of the hardware supported values is lower than that of the
> control. Could you add try_ctrl op to provide the actual value back to the
> user space?

Tbh, I've never implemented a try_ctrl before, but sure. I will dig into it and
add it for the ov9282 FLASH_DURATION in v4.

> 
> > +}
> > +
> >  /**
> >   * 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,
> 
> Should the number of controls in the handler be updated?

What do you mean by "number of controls in the handler" exactly? Which
handler?

> > +			  0, 13900, 1, 8);
> > +
> >  	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
> >  	if (!ret) {
> >  		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */
> > 
> 
> -- 
> Regards,
> 
> Sakari Ailus

regards;rl

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

[Sakari Ailus]

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.

-- 
Regards,

Sakari Ailus

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

[Richard Leitner]

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

[PATCH v3 9/9] media: i2c: ov9282: add strobe_source v4l2 control

[Richard Leitner]

Add read-only V4L2_CID_FLASH_STROBE_SOURCE control. Its value is fixed
to V4L2_FLASH_STROBE_SOURCE_EXTERNAL as the camera sensor triggers the
strobe based on its register settings.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/i2c/ov9282.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index 5ddbfc51586111fbd2e17b739fb3d28bfb0aee1e..34ea903a18dadeeebd497a4a8858abf12b598717 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -1367,6 +1367,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
 	struct v4l2_ctrl_handler *ctrl_hdlr = &ov9282->ctrl_handler;
 	const struct ov9282_mode *mode = ov9282->cur_mode;
 	struct v4l2_fwnode_device_properties props;
+	struct v4l2_ctrl *ctrl;
 	u32 hblank_min;
 	u32 lpfr;
 	int ret;
@@ -1446,6 +1447,13 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
 	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
 			  0, 13900, 1, 8);
 
+	ctrl = v4l2_ctrl_new_std_menu(ctrl_hdlr, &ov9282_ctrl_ops,
+				      V4L2_CID_FLASH_STROBE_SOURCE,
+				      V4L2_FLASH_STROBE_SOURCE_EXTERNAL,
+				      ~(1 << V4L2_FLASH_STROBE_SOURCE_EXTERNAL),
+				      V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
+	ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
+
 	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
 	if (!ret) {
 		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */

-- 
2.47.2

Re: [PATCH v3 9/9] media: i2c: ov9282: add strobe_source v4l2 control

[Sakari Ailus]

Hi Richard,

On Tue, Apr 29, 2025 at 02:59:14PM +0200, Richard Leitner wrote:
> Add read-only V4L2_CID_FLASH_STROBE_SOURCE control. Its value is fixed
> to V4L2_FLASH_STROBE_SOURCE_EXTERNAL as the camera sensor triggers the
> strobe based on its register settings.
> 
> Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
> ---
>  drivers/media/i2c/ov9282.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> index 5ddbfc51586111fbd2e17b739fb3d28bfb0aee1e..34ea903a18dadeeebd497a4a8858abf12b598717 100644
> --- a/drivers/media/i2c/ov9282.c
> +++ b/drivers/media/i2c/ov9282.c
> @@ -1367,6 +1367,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
>  	struct v4l2_ctrl_handler *ctrl_hdlr = &ov9282->ctrl_handler;
>  	const struct ov9282_mode *mode = ov9282->cur_mode;
>  	struct v4l2_fwnode_device_properties props;
> +	struct v4l2_ctrl *ctrl;
>  	u32 hblank_min;
>  	u32 lpfr;
>  	int ret;
> @@ -1446,6 +1447,13 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
>  	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
>  			  0, 13900, 1, 8);
>  
> +	ctrl = v4l2_ctrl_new_std_menu(ctrl_hdlr, &ov9282_ctrl_ops,
> +				      V4L2_CID_FLASH_STROBE_SOURCE,
> +				      V4L2_FLASH_STROBE_SOURCE_EXTERNAL,
> +				      ~(1 << V4L2_FLASH_STROBE_SOURCE_EXTERNAL),
> +				      V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
> +	ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;

Note that v4l2_ctrl_new_std_menu() may return NULL.

> +
>  	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
>  	if (!ret) {
>  		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */
> 

-- 
Sakari Ailus

Re: [PATCH v3 9/9] media: i2c: ov9282: add strobe_source v4l2 control

[Richard Leitner]

Hi Sakari,

thanks for your comment!

On Wed, Apr 30, 2025 at 08:39:43AM +0000, Sakari Ailus wrote:
> Hi Richard,
> 
> On Tue, Apr 29, 2025 at 02:59:14PM +0200, Richard Leitner wrote:
> > Add read-only V4L2_CID_FLASH_STROBE_SOURCE control. Its value is fixed
> > to V4L2_FLASH_STROBE_SOURCE_EXTERNAL as the camera sensor triggers the
> > strobe based on its register settings.
> > 
> > Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
> > ---
> >  drivers/media/i2c/ov9282.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> > index 5ddbfc51586111fbd2e17b739fb3d28bfb0aee1e..34ea903a18dadeeebd497a4a8858abf12b598717 100644
> > --- a/drivers/media/i2c/ov9282.c
> > +++ b/drivers/media/i2c/ov9282.c
> > @@ -1367,6 +1367,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
> >  	struct v4l2_ctrl_handler *ctrl_hdlr = &ov9282->ctrl_handler;
> >  	const struct ov9282_mode *mode = ov9282->cur_mode;
> >  	struct v4l2_fwnode_device_properties props;
> > +	struct v4l2_ctrl *ctrl;
> >  	u32 hblank_min;
> >  	u32 lpfr;
> >  	int ret;
> > @@ -1446,6 +1447,13 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
> >  	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> >  			  0, 13900, 1, 8);
> >  
> > +	ctrl = v4l2_ctrl_new_std_menu(ctrl_hdlr, &ov9282_ctrl_ops,
> > +				      V4L2_CID_FLASH_STROBE_SOURCE,
> > +				      V4L2_FLASH_STROBE_SOURCE_EXTERNAL,
> > +				      ~(1 << V4L2_FLASH_STROBE_SOURCE_EXTERNAL),
> > +				      V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
> > +	ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> 
> Note that v4l2_ctrl_new_std_menu() may return NULL.

Good catch. Thanks! Will add a check in v4.

> 
> > +
> >  	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
> >  	if (!ret) {
> >  		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */
> > 
> 
> -- 
> Sakari Ailus

regards;rl