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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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