Re: [RFC v5 06/15] media: uapi: Add V4L2_CID_CONFIG_MODEL control

Hans Verkuil
2025-02-10T09:09:40Z

Hi Sakari,

On 03/02/2025 09:58, Sakari Ailus wrote:
> Add the V4L2_CID_CONFIG_MODEL control for the configuration model.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
> .../userspace-api/media/v4l/ext-ctrls-image-process.rst | 4 ++++
> drivers/media/v4l2-core/v4l2-ctrls-defs.c | 5 +++++
> include/uapi/linux/v4l2-controls.h | 3 +++
> 3 files changed, 12 insertions(+)
>
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> index 27803dca8d3e..2ae17ed99729 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> @@ -55,3 +55,7 @@ Image Process Control IDs
> control value divided by e.g. 0x100, meaning that to get no
> digital gain the control value needs to be 0x100. The no-gain
> configuration is also typically the default.
> +
> +``V4L2_CID_CONFIG_MODEL (bitmask)``
> + Which configuration models the sub-device supports. Please see
> + :ref:`media_subdev_config_model`. This is a read-only control.
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> index 1ea52011247a..24c9c25e20d1 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
> @@ -1164,6 +1164,7 @@ const char *v4l2_ctrl_get_name(u32 id)
> case V4L2_CID_TEST_PATTERN: return "Test Pattern";
> case V4L2_CID_DEINTERLACING_MODE: return "Deinterlacing Mode";
> case V4L2_CID_DIGITAL_GAIN: return "Digital Gain";
> + case V4L2_CID_CONFIG_MODEL: return "Sub-device configuration model";
>
> /* DV controls */
> /* Keep the order of the 'case's the same as in v4l2-controls.h! */
> @@ -1481,6 +1482,10 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
> case V4L2_CID_DV_RX_POWER_PRESENT:
> *type = V4L2_CTRL_TYPE_BITMASK;
> break;
> + case V4L2_CID_CONFIG_MODEL:
> + *flags |= V4L2_CTRL_FLAG_READ_ONLY;
> + *type = V4L2_CTRL_TYPE_BITMASK;
> + break;
> case V4L2_CID_MIN_BUFFERS_FOR_CAPTURE:
> case V4L2_CID_MIN_BUFFERS_FOR_OUTPUT:
> *type = V4L2_CTRL_TYPE_INTEGER;
> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
> index 974fd254e573..731add75d9ee 100644
> --- a/include/uapi/linux/v4l2-controls.h
> +++ b/include/uapi/linux/v4l2-controls.h
> @@ -1225,6 +1225,9 @@ enum v4l2_jpeg_chroma_subsampling {
> #define V4L2_CID_TEST_PATTERN (V4L2_CID_IMAGE_PROC_CLASS_BASE + 3)
> #define V4L2_CID_DEINTERLACING_MODE (V4L2_CID_IMAGE_PROC_CLASS_BASE + 4)
> #define V4L2_CID_DIGITAL_GAIN (V4L2_CID_IMAGE_PROC_CLASS_BASE + 5)
> +#define V4L2_CID_CONFIG_MODEL (V4L2_CID_IMAGE_PROC_CLASS_BASE + 6)
> +
> +#define V4L2_CID_CONFIG_MODEL_COMMON_RAW (1U << 0)

I think I mentioned this before, but what's the point of this?

You are adding a control describing a configuration model, but it has just a single
possible configuration model. I see no description anywhere about when a new model
would need to be added, or what userspace is supposed to do with this.

And as long as there is only one model anyway, I don't see the point of this control.

Is the intention that all sensor drivers will set this control? The RFC series isn't
clear about this.

The problem I see with this series is that it seems to mix seemingly unrelated changes:
adding COLOUR_PATTERN/BINNING controls doesn't seem to depend on configuration models.
Or if they do, I clearly didn't get that.

Regards,

Hans

>
> /* DV-class control IDs defined by V4L2 */
> #define V4L2_CID_DV_CLASS_BASE (V4L2_CTRL_CLASS_DV | 0x900)