linux-kernel - Re: [PATCH 2/6] media: uvcvideo: Add UVC_CTRL_FLAG_ENTITY_GET

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Message-ID: <20201104111253.GA6196@pendragon.ideasonboard.com>
Date:   Wed, 4 Nov 2020 13:12:53 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Ricardo Ribalda <ribalda@...omium.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        tfiga@...omium.org
Subject: Re: [PATCH 2/6] media: uvcvideo: Add UVC_CTRL_FLAG_ENTITY_GET_CUR

Hi Ricardo,

Thank you for the patch.

On Thu, Oct 22, 2020 at 03:37:49PM +0200, Ricardo Ribalda wrote:
> This flag allows controls to get their current value from an entity
> defined function instead of via a query to the USB device.
> 
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/usb/uvc/uvc_ctrl.c | 17 +++++++++++++----
>  include/uapi/linux/uvcvideo.h    |  1 +
>  2 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 7acdc055613b..0a8835742d49 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1001,10 +1001,19 @@ static int __uvc_ctrl_get(struct uvc_video_chain *chain,
>  		return -EACCES;
>  
>  	if (!ctrl->loaded) {
> -		ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR, ctrl->entity->id,
> -				chain->dev->intfnum, ctrl->info.selector,
> -				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
> -				ctrl->info.size);
> +		if (ctrl->info.flags & UVC_CTRL_FLAG_ENTITY_GET_CUR) {

Same question as for 2/6, do we need this flag ?

> +			if (!ctrl->entity->get_cur)
> +				return -EINVAL;
> +			ret = ctrl->entity->get_cur(ctrl->entity,
> +					ctrl->info.selector,
> +					uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
> +					ctrl->info.size);
> +		} else {
> +			ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR, ctrl->entity->id,
> +					     chain->dev->intfnum, ctrl->info.selector,
> +					     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
> +					     ctrl->info.size);
> +		}
>  		if (ret < 0)
>  			return ret;
>  
> diff --git a/include/uapi/linux/uvcvideo.h b/include/uapi/linux/uvcvideo.h
> index 69b636290c31..cb91797d2a09 100644
> --- a/include/uapi/linux/uvcvideo.h
> +++ b/include/uapi/linux/uvcvideo.h
> @@ -32,6 +32,7 @@
>  #define UVC_CTRL_FLAG_ASYNCHRONOUS	(1 << 8)
>  /* Entity queries */
>  #define UVC_CTRL_FLAG_ENTITY_GET_INFO	(1 << 9)
> +#define UVC_CTRL_FLAG_ENTITY_GET_CUR	(1 << 10)
>  
>  #define UVC_CTRL_FLAG_GET_RANGE \
>  	(UVC_CTRL_FLAG_GET_CUR | UVC_CTRL_FLAG_GET_MIN | \

-- 
Regards,

Laurent Pinchart