linux-kernel - Re: [PATCH v2 10/12] media: uvcvideo: Add get_* functions to uvc

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Message-ID: <20250629181246.GE6260@pendragon.ideasonboard.com>
Date: Sun, 29 Jun 2025 21:12:46 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Hans de Goede <hdegoede@...hat.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	devicetree@...r.kernel.org, linux-gpio@...r.kernel.org,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH v2 10/12] media: uvcvideo: Add get_* functions to
 uvc_entity

Hi Ricardo,

Thank you for the patch.

On Thu, Jun 05, 2025 at 05:53:03PM +0000, Ricardo Ribalda wrote:
> Virtual entities need to provide more values than get_cur and get_cur

I think you meant "get_info and get_cur".

> for their controls. Add support for get_def, get_min, get_max and
> get_res.

Do they ? The UVC specification defines controls that don't list
GET_DEF, GET_MIN, GET_MAX and GET_RES as mandatory requests. Can't we do
the same for the software controls ? This patch is meant to support the
UVC_SWENTITY_ORIENTATION and UVC_SWENTITY_ROTATION control in the next
patch, and those are read-only controls. Aren't GET_INFO and GET_CUR
enough ?

> 
> This is a preparation patch.
> 
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/usb/uvc/uvc_ctrl.c | 12 ++++++++++++
>  drivers/media/usb/uvc/uvcvideo.h |  8 ++++++++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 21ec7b978bc7aca21db7cb8fd5d135d876f3330c..59be62ae24a4219fa9d7aacf2ae7382c95362178 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -596,6 +596,18 @@ static int uvc_ctrl_query_entity(struct uvc_device *dev,
>  	if (query == UVC_GET_CUR && ctrl->entity->get_cur)
>  		return ctrl->entity->get_cur(dev, ctrl->entity,
>  					     ctrl->info.selector, data, len);
> +	if (query == UVC_GET_DEF && ctrl->entity->get_def)
> +		return ctrl->entity->get_def(dev, ctrl->entity,
> +					     ctrl->info.selector, data, len);
> +	if (query == UVC_GET_MIN && ctrl->entity->get_min)
> +		return ctrl->entity->get_min(dev, ctrl->entity,
> +					     ctrl->info.selector, data, len);
> +	if (query == UVC_GET_MAX && ctrl->entity->get_max)
> +		return ctrl->entity->get_max(dev, ctrl->entity,
> +					     ctrl->info.selector, data, len);
> +	if (query == UVC_GET_RES && ctrl->entity->get_res)
> +		return ctrl->entity->get_res(dev, ctrl->entity,
> +					     ctrl->info.selector, data, len);
>  	if (query == UVC_GET_INFO && ctrl->entity->get_info)
>  		return ctrl->entity->get_info(dev, ctrl->entity,
>  					      ctrl->info.selector, data);
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index a931750bdea25b9062dcc7644bf5f2ed89c1cb4c..d6da8ed3ad4cf3377df49923e051fe04d83d2e38 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -261,6 +261,14 @@ struct uvc_entity {
>  			u8 cs, u8 *caps);
>  	int (*get_cur)(struct uvc_device *dev, struct uvc_entity *entity,
>  		       u8 cs, void *data, u16 size);
> +	int (*get_def)(struct uvc_device *dev, struct uvc_entity *entity,
> +		       u8 cs, void *data, u16 size);
> +	int (*get_min)(struct uvc_device *dev, struct uvc_entity *entity,
> +		       u8 cs, void *data, u16 size);
> +	int (*get_max)(struct uvc_device *dev, struct uvc_entity *entity,
> +		       u8 cs, void *data, u16 size);
> +	int (*get_res)(struct uvc_device *dev, struct uvc_entity *entity,
> +		       u8 cs, void *data, u16 size);
>  
>  	unsigned int ncontrols;
>  	struct uvc_control *controls;

-- 
Regards,

Laurent Pinchart