linux-kernel - Re: [PATCH 1/6] media: uvcvideo: Add UVC_CTRL_FLAG_ENTITY_GET

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Message-ID: <20201104110937.GH26171@pendragon.ideasonboard.com>
Date:   Wed, 4 Nov 2020 13:09:37 +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 1/6] media: uvcvideo: Add UVC_CTRL_FLAG_ENTITY_GET_INFO

Hi Ricardo,

Thank you for the patch.

On Thu, Oct 22, 2020 at 03:37:48PM +0200, Ricardo Ribalda wrote:
> This flag allows controls to get their properties from an entity defined

s/entity defined/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 | 9 +++++++--
>  drivers/media/usb/uvc/uvcvideo.h | 3 +++
>  include/uapi/linux/uvcvideo.h    | 2 ++
>  3 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index f479d8971dfb..7acdc055613b 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1708,8 +1708,13 @@ static int uvc_ctrl_get_flags(struct uvc_device *dev,
>  	if (data == NULL)
>  		return -ENOMEM;
>  
> -	ret = uvc_query_ctrl(dev, UVC_GET_INFO, ctrl->entity->id, dev->intfnum,
> -			     info->selector, data, 1);
> +	if (ctrl->info.flags & UVC_CTRL_FLAG_ENTITY_GET_INFO)

Do we need the flag, couldn't we use entity->get_info if it is non-null,
and call uvc_query_ctrl() otherwise ?

> +		ret = ctrl->entity->get_info ?
> +			ctrl->entity->get_info(ctrl->entity, ctrl->info.selector, data) :
> +			-EINVAL;
> +	else
> +		ret = uvc_query_ctrl(dev, UVC_GET_INFO, ctrl->entity->id, dev->intfnum,
> +				     info->selector, data, 1);
>  	if (!ret)
>  		info->flags |= (data[0] & UVC_CONTROL_CAP_GET ?
>  				UVC_CTRL_FLAG_GET_CUR : 0)
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index a3dfacf069c4..08922d889bb6 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -353,6 +353,9 @@ struct uvc_entity {
>  	u8 bNrInPins;
>  	u8 *baSourceID;
>  
> +	int (*get_info)(struct uvc_entity *entity, u8 cs, u8 *caps);
> +	int (*get_cur)(struct uvc_entity *entity, u8 cs, void *data, u16 size);

Looks like the second function should be part of patch 2/6 instead. I
would however squash 1/6 and 2/6.

> +
>  	unsigned int ncontrols;
>  	struct uvc_control *controls;
>  };
> diff --git a/include/uapi/linux/uvcvideo.h b/include/uapi/linux/uvcvideo.h
> index f80f05b3c423..69b636290c31 100644
> --- a/include/uapi/linux/uvcvideo.h
> +++ b/include/uapi/linux/uvcvideo.h
> @@ -30,6 +30,8 @@
>  #define UVC_CTRL_FLAG_AUTO_UPDATE	(1 << 7)
>  /* Control supports asynchronous reporting */
>  #define UVC_CTRL_FLAG_ASYNCHRONOUS	(1 << 8)
> +/* Entity queries */
> +#define UVC_CTRL_FLAG_ENTITY_GET_INFO	(1 << 9)
>  
>  #define UVC_CTRL_FLAG_GET_RANGE \
>  	(UVC_CTRL_FLAG_GET_CUR | UVC_CTRL_FLAG_GET_MIN | \

-- 
Regards,

Laurent Pinchart