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Message-ID: <20250629175045.GC6260@pendragon.ideasonboard.com>
Date: Sun, 29 Jun 2025 20:50:45 +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 08/12] media: uvcvideo: Add support for
 V4L2_CID_CAMERA_ORIENTATION

Hi Ricardo,

On Thu, Jun 05, 2025 at 05:53:01PM +0000, Ricardo Ribalda wrote:
> Fetch the orientation from the fwnode and map it into a control.
> 
> The uvc driver does not use the media controller, so we need to create a
> virtual entity, like we previously did with the external gpio.
> 
> We do not re-purpose the external gpio entity because its is planned to
> remove it.

Comparing the GUIDs for the EXT_GPIO_CONTROLLER and SWENTITY, we have

#define UVC_GUID_EXT_GPIO_CONTROLLER \
	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03}
#define UVC_GUID_SWENTITY \
	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x04}

The GUIDs don't carry any special meaning in their values. I agree with
the plan to drop the existing features of the GPIO entity, but wouldn't
it be easier to rename UVC_GUID_EXT_GPIO_CONTROLLER to UVC_GUID_SWENTITY
and UVC_EXT_GPIO_UNIT* to UVC_SWENTITY_UNIT* (the macros are not exposed
to userspace), and later drop the existing GPIO controls from the entity
?

> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/usb/uvc/Makefile       |  3 +-
>  drivers/media/usb/uvc/uvc_ctrl.c     | 21 +++++++++++
>  drivers/media/usb/uvc/uvc_driver.c   | 14 +++++--
>  drivers/media/usb/uvc/uvc_entity.c   |  1 +
>  drivers/media/usb/uvc/uvc_swentity.c | 73 ++++++++++++++++++++++++++++++++++++
>  drivers/media/usb/uvc/uvcvideo.h     | 14 +++++++
>  include/linux/usb/uvc.h              |  3 ++
>  7 files changed, 125 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/Makefile b/drivers/media/usb/uvc/Makefile
> index 4f9eee4f81ab6436a8b90324a688a149b2c3bcd1..b4398177c4bb0a9bd49dfd4ca7f2e933b4a1d7df 100644
> --- a/drivers/media/usb/uvc/Makefile
> +++ b/drivers/media/usb/uvc/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  uvcvideo-objs  := uvc_driver.o uvc_queue.o uvc_v4l2.o uvc_video.o uvc_ctrl.o \
> -		  uvc_status.o uvc_isight.o uvc_debugfs.o uvc_metadata.o
> +		  uvc_status.o uvc_isight.o uvc_debugfs.o uvc_metadata.o \
> +		  uvc_swentity.o
>  ifeq ($(CONFIG_MEDIA_CONTROLLER),y)
>  uvcvideo-objs  += uvc_entity.o
>  endif
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 47e8ccc39234d1769384b55539a21df07f3d57c7..b2768080c08aafa85acb9b7f318672c043d84e55 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -376,6 +376,13 @@ static const struct uvc_control_info uvc_ctrls[] = {
>  				| UVC_CTRL_FLAG_GET_DEF
>  				| UVC_CTRL_FLAG_AUTO_UPDATE,
>  	},
> +	{
> +		.entity		= UVC_GUID_SWENTITY,
> +		.selector	= 0,
> +		.index		= 0,
> +		.size		= 1,
> +		.flags		= UVC_CTRL_FLAG_GET_CUR,
> +	},
>  };
>  
>  static const u32 uvc_control_classes[] = {
> @@ -975,6 +982,17 @@ static const struct uvc_control_mapping uvc_ctrl_mappings[] = {
>  		.data_type	= UVC_CTRL_DATA_TYPE_BITMASK,
>  		.name		= "Region of Interest Auto Ctrls",
>  	},
> +	{
> +		.id		= V4L2_CID_CAMERA_ORIENTATION,
> +		.entity		= UVC_GUID_SWENTITY,
> +		.selector	= 0,
> +		.size		= 8,
> +		.offset		= 0,
> +		.v4l2_type	= V4L2_CTRL_TYPE_MENU,
> +		.data_type	= UVC_CTRL_DATA_TYPE_ENUM,
> +		.menu_mask	= GENMASK(V4L2_CAMERA_ORIENTATION_EXTERNAL,
> +					  V4L2_CAMERA_ORIENTATION_FRONT),
> +	},
>  };
>  
>  /* ------------------------------------------------------------------------
> @@ -3210,6 +3228,9 @@ static int uvc_ctrl_init_chain(struct uvc_video_chain *chain)
>  		} else if (UVC_ENTITY_TYPE(entity) == UVC_EXT_GPIO_UNIT) {
>  			bmControls = entity->gpio.bmControls;
>  			bControlSize = entity->gpio.bControlSize;
> +		} else if (UVC_ENTITY_TYPE(entity) == UVC_SWENTITY_UNIT) {
> +			bmControls = entity->swentity.bmControls;
> +			bControlSize = entity->swentity.bControlSize;
>  		}
>  
>  		/* Remove bogus/blacklisted controls */
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index bcc97f71fa1703aea1119469fb32659c17d9409a..96eeb3aee546487d15f3c30dfe1775189ddf7e47 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -1869,11 +1869,15 @@ static int uvc_scan_device(struct uvc_device *dev)
>  		return -1;
>  	}
>  
> -	/* Add GPIO entity to the first chain. */
> -	if (dev->gpio_unit) {
> +	/* Add virtual entities to the first chain. */
> +	if (dev->gpio_unit || dev->swentity_unit) {
>  		chain = list_first_entry(&dev->chains,
>  					 struct uvc_video_chain, list);
> -		list_add_tail(&dev->gpio_unit->chain, &chain->entities);
> +		if (dev->gpio_unit)
> +			list_add_tail(&dev->gpio_unit->chain, &chain->entities);
> +		if (dev->swentity_unit)
> +			list_add_tail(&dev->swentity_unit->chain,
> +				      &chain->entities);
>  	}
>  
>  	return 0;
> @@ -2249,6 +2253,10 @@ static int uvc_probe(struct usb_interface *intf,
>  	if (ret < 0)
>  		goto error;
>  
> +	ret = uvc_swentity_init(dev);
> +	if (ret < 0)
> +		goto error;
> +
>  	dev_info(&dev->udev->dev, "Found UVC %u.%02x device %s (%04x:%04x)\n",
>  		 dev->uvc_version >> 8, dev->uvc_version & 0xff,
>  		 udev->product ? udev->product : "<unnamed>",
> diff --git a/drivers/media/usb/uvc/uvc_entity.c b/drivers/media/usb/uvc/uvc_entity.c
> index cc68dd24eb42dce5b2846ca52a8dfa499c8aed96..d1a652ef35ec34801bd39a5124b834edf838a79e 100644
> --- a/drivers/media/usb/uvc/uvc_entity.c
> +++ b/drivers/media/usb/uvc/uvc_entity.c
> @@ -106,6 +106,7 @@ static int uvc_mc_init_entity(struct uvc_video_chain *chain,
>  		case UVC_OTT_MEDIA_TRANSPORT_OUTPUT:
>  		case UVC_EXTERNAL_VENDOR_SPECIFIC:
>  		case UVC_EXT_GPIO_UNIT:
> +		case UVC_SWENTITY_UNIT:
>  		default:
>  			function = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
>  			break;
> diff --git a/drivers/media/usb/uvc/uvc_swentity.c b/drivers/media/usb/uvc/uvc_swentity.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..702a2c26e029a0655dade177ed2a9b88d7a4136d
> --- /dev/null
> +++ b/drivers/media/usb/uvc/uvc_swentity.c
> @@ -0,0 +1,73 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + *      uvc_swentity.c  --  USB Video Class driver
> + *
> + *      Copyright 2025 Google LLC
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/usb/uvc.h>
> +#include <media/v4l2-fwnode.h>
> +#include "uvcvideo.h"

Blank lines between header groups would be nice.

> +
> +static int uvc_swentity_get_cur(struct uvc_device *dev, struct uvc_entity *entity,
> +				u8 cs, void *data, u16 size)
> +{
> +	if (size < 1)
> +		return -EINVAL;
> +
> +	switch (entity->swentity.props.orientation) {
> +	case V4L2_FWNODE_ORIENTATION_FRONT:
> +		*(u8 *)data = V4L2_CAMERA_ORIENTATION_FRONT;
> +		break;
> +	case V4L2_FWNODE_ORIENTATION_BACK:
> +		*(u8 *)data = V4L2_CAMERA_ORIENTATION_BACK;
> +		break;
> +	default:
> +		*(u8 *)data = V4L2_CAMERA_ORIENTATION_EXTERNAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int uvc_swentity_get_info(struct uvc_device *dev,
> +				 struct uvc_entity *entity, u8 cs, u8 *caps)
> +{
> +	*caps = UVC_CONTROL_CAP_GET;
> +	return 0;
> +}
> +
> +int uvc_swentity_init(struct uvc_device *dev)
> +{
> +	static const u8 uvc_swentity_guid[] = UVC_GUID_SWENTITY;
> +	struct v4l2_fwnode_device_properties props;
> +	struct uvc_entity *unit;
> +	int ret;
> +
> +	ret = v4l2_fwnode_device_parse(&dev->udev->dev, &props);
> +	if (ret)
> +		return dev_err_probe(&dev->intf->dev, ret,
> +				     "Can't parse fwnode\n");
> +
> +	if (props.orientation == V4L2_FWNODE_PROPERTY_UNSET)
> +		return 0;
> +
> +	unit = uvc_alloc_entity(UVC_SWENTITY_UNIT, UVC_SWENTITY_UNIT_ID, 0, 1);
> +	if (!unit)
> +		return -ENOMEM;
> +
> +	memcpy(unit->guid, uvc_swentity_guid, sizeof(unit->guid));
> +	unit->swentity.props = props;
> +	unit->swentity.bControlSize = 1;
> +	unit->swentity.bmControls = (u8 *)unit + sizeof(*unit);
> +	unit->swentity.bmControls[0] = 1;
> +	unit->get_cur = uvc_swentity_get_cur;
> +	unit->get_info = uvc_swentity_get_info;
> +	strscpy(unit->name, "SWENTITY", sizeof(unit->name));
> +
> +	list_add_tail(&unit->list, &dev->entities);
> +
> +	dev->swentity_unit = unit;
> +
> +	return 0;
> +}
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index dc23d8a97340dc4615d4182232d395106e6d9ed5..a931750bdea25b9062dcc7644bf5f2ed89c1cb4c 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -19,6 +19,7 @@
>  #include <media/v4l2-event.h>
>  #include <media/v4l2-fh.h>
>  #include <media/videobuf2-v4l2.h>
> +#include <media/v4l2-fwnode.h>

Alphabetical order.

>  
>  /* --------------------------------------------------------------------------
>   * UVC constants
> @@ -41,6 +42,9 @@
>  #define UVC_EXT_GPIO_UNIT		0x7ffe
>  #define UVC_EXT_GPIO_UNIT_ID		0x100
>  
> +#define UVC_SWENTITY_UNIT		0x7ffd
> +#define UVC_SWENTITY_UNIT_ID		0x101
> +
>  /* ------------------------------------------------------------------------
>   * Driver specific constants.
>   */
> @@ -242,6 +246,12 @@ struct uvc_entity {
>  			int irq;
>  			bool initialized;
>  		} gpio;
> +
> +		struct {
> +			u8  bControlSize;
> +			u8  *bmControls;
> +			struct v4l2_fwnode_device_properties props;
> +		} swentity;
>  	};
>  
>  	u8 bNrInPins;
> @@ -617,6 +627,7 @@ struct uvc_device {
>  	} async_ctrl;
>  
>  	struct uvc_entity *gpio_unit;
> +	struct uvc_entity *swentity_unit;
>  };
>  
>  enum uvc_handle_state {
> @@ -836,4 +847,7 @@ void uvc_debugfs_cleanup_stream(struct uvc_streaming *stream);
>  size_t uvc_video_stats_dump(struct uvc_streaming *stream, char *buf,
>  			    size_t size);
>  
> +/* swentity */
> +int uvc_swentity_init(struct uvc_device *dev);
> +
>  #endif
> diff --git a/include/linux/usb/uvc.h b/include/linux/usb/uvc.h
> index bce95153e5a65613a710d7316fc17cf5462b5bce..88a23e8919d1294da4308e0e3ca0eccdc66a318f 100644
> --- a/include/linux/usb/uvc.h
> +++ b/include/linux/usb/uvc.h
> @@ -29,6 +29,9 @@
>  #define UVC_GUID_EXT_GPIO_CONTROLLER \
>  	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
>  	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03}
> +#define UVC_GUID_SWENTITY \
> +	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
> +	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x04}
>  
>  #define UVC_GUID_FORMAT_MJPEG \
>  	{ 'M',  'J',  'P',  'G', 0x00, 0x00, 0x10, 0x00, \

-- 
Regards,

Laurent Pinchart

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