Re: [PATCH] media: uvcvideo: Fix custom control mapping probing

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Ricardo,

Thank you for the patch.

On Mon, Jul 22, 2024 at 07:59:43AM +0000, Ricardo Ribalda wrote:
> Custom control mapping introduced a bug, where the filter function was
> applied to every single control.
> 
> Fix it so it is only applied to the matching controls.
> 
> Reported-by: Paul Menzen <pmenzel@molgen.mpg.de>
> Closes: https://lore.kernel.org/linux-media/518cd6b4-68a8-4895-b8fc-97d4dae1ddc4@molgen.mpg.de/T/#t
> Cc: stable@vger.kernel.org
> Fixes: 8f4362a8d42b ("media: uvcvideo: Allow custom control mapping")
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> Paul, could you check if this fixes your issue, thanks!
> ---
>  drivers/media/usb/uvc/uvc_ctrl.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 0136df5732ba..06fede57bf36 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -2680,6 +2680,10 @@ static void uvc_ctrl_init_ctrl(struct uvc_video_chain *chain,
>  	for (i = 0; i < ARRAY_SIZE(uvc_ctrl_mappings); ++i) {
>  		const struct uvc_control_mapping *mapping = &uvc_ctrl_mappings[i];
>  
> +		if (!(uvc_entity_match_guid(ctrl->entity, mapping->entity) &&
> +		    ctrl->info.selector == mapping->selector))
> +			continue;

I have a slight preference for

		if (!uvc_entity_match_guid(ctrl->entity, mapping->entity) ||
		    ctrl->info.selector != mapping->selector)
			continue;

If that's fine with you, I can handle that when applying the patch.

This change means that the entity and selector test will use the
original mapping, not the mapping returned by the filtering function. I
think that's fine, both mappings should have the same entity and
selector, only the menu mask is meant to change.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> +
>  		/* Let the device provide a custom mapping. */
>  		if (mapping->filter_mapping) {
>  			mapping = mapping->filter_mapping(chain, ctrl);
> @@ -2687,9 +2691,7 @@ static void uvc_ctrl_init_ctrl(struct uvc_video_chain *chain,
>  				continue;
>  		}
>  
> -		if (uvc_entity_match_guid(ctrl->entity, mapping->entity) &&
> -		    ctrl->info.selector == mapping->selector)
> -			__uvc_ctrl_add_mapping(chain, ctrl, mapping);
> +		__uvc_ctrl_add_mapping(chain, ctrl, mapping);
>  	}
>  }
>  
> 
> ---
> base-commit: 68a72104cbcf38ad16500216e213fa4eb21c4be2
> change-id: 20240722-fix-filter-mapping-18477dc69048

-- 
Regards,

Laurent Pinchart