Re: [PATCH 5.10 427/491] media: uvcvideo: Implement UVC_EXT_GPIO_UNIT

Ben Hutchings
2026-04-13T20:43:13Z

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On Mon, 2026-04-13 at 18:01 +0200, Greg Kroah-Hartman wrote:
> 5.10-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Ricardo Ribalda <ribalda@chromium.org>
>
> [ Upstream commit 2886477ff98740cc3333cf785e4de0b1ff3d7a28 ]

This is a new feature, not obviously suitable for stable.

If it really is needed for 5.10 then there are a number of bug fixes
that also need to follow: 387e89393071 ["media: uvcvideo: Fix deferred
probing error"), a9ea1a3d88b7 ("media: uvcvideo: Fix crash during unbind
if gpio unit is in use"), and f0f078457f18 ("media: uvcvideo: Fix memory
leak in uvc_gpio_parse").

Ben.

> Some devices can implement a physical switch to disable the input of the
> camera on demand. Think of it like an elegant privacy sticker.
>
> The system can read the status of the privacy switch via a GPIO.
>
> It is important to know the status of the switch, e.g. to notify the
> user when the camera will produce black frames and a videochat
> application is used.
>
> In some systems, the GPIO is connected to the main SoC instead of the
> camera controller, with the connection reported by the system firmware
> (ACPI or DT). In that case, the UVC device isn't aware of the GPIO. We
> need to implement a virtual entity to handle the GPIO fully on the
> driver side.
>
> For example, for ACPI-based systems, the GPIO is reported in the USB
> device object:
>
> Scope (\_SB.PCI0.XHCI.RHUB.HS07)
> {
>
> /.../
>
> Name (_CRS, ResourceTemplate () // _CRS: Current Resource Settings
> {
> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> "\\_SB.PCI0.GPIO", 0x00, ResourceConsumer, ,
> )
> { // Pin list
> 0x0064
> }
> })
> Name (_DSD, Package (0x02) // _DSD: Device-Specific Data
> {
> ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device Properties for _DSD */,
> Package (0x01)
> {
> Package (0x02)
> {
> "privacy-gpio",
> Package (0x04)
> {
> \_SB.PCI0.XHCI.RHUB.HS07,
> Zero,
> Zero,
> One
> }
> }
> }
> })
> }
>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> Stable-dep-of: 0e2ee70291e6 ("media: uvcvideo: Mark invalid entities with id UVC_INVALID_ENTITY_ID")
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 3 +
> drivers/media/usb/uvc/uvc_driver.c | 127 +++++++++++++++++++++++++++++
> drivers/media/usb/uvc/uvc_entity.c | 1 +
> drivers/media/usb/uvc/uvcvideo.h | 16 ++++
> 4 files changed, 147 insertions(+)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 698bf5bb896ec..fc23e53c0d38b 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -2378,6 +2378,9 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
> } else if (UVC_ENTITY_TYPE(entity) == UVC_ITT_CAMERA) {
> bmControls = entity->camera.bmControls;
> bControlSize = entity->camera.bControlSize;
> + } else if (UVC_ENTITY_TYPE(entity) == UVC_EXT_GPIO_UNIT) {
> + bmControls = entity->gpio.bmControls;
> + bControlSize = entity->gpio.bControlSize;
> }
>
> /* Remove bogus/blacklisted controls */
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index e1d3e753e80ed..b86e46fa7c0af 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -7,6 +7,7 @@
> */
>
> #include <linux/atomic.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/kernel.h>
> #include <linux/list.h>
> #include <linux/module.h>
> @@ -1033,6 +1034,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
> }
>
> static const u8 uvc_camera_guid[16] = UVC_GUID_UVC_CAMERA;
> +static const u8 uvc_gpio_guid[16] = UVC_GUID_EXT_GPIO_CONTROLLER;
> static const u8 uvc_media_transport_input_guid[16] =
> UVC_GUID_UVC_MEDIA_TRANSPORT_INPUT;
> static const u8 uvc_processing_guid[16] = UVC_GUID_UVC_PROCESSING;
> @@ -1064,6 +1066,9 @@ static struct uvc_entity *uvc_alloc_entity(u16 type, u16 id,
> * is initialized by the caller.
> */
> switch (type) {
> + case UVC_EXT_GPIO_UNIT:
> + memcpy(entity->guid, uvc_gpio_guid, 16);
> + break;
> case UVC_ITT_CAMERA:
> memcpy(entity->guid, uvc_camera_guid, 16);
> break;
> @@ -1467,6 +1472,108 @@ static int uvc_parse_control(struct uvc_device *dev)
> return 0;
> }
>
> +/* -----------------------------------------------------------------------------
> + * Privacy GPIO
> + */
> +
> +static void uvc_gpio_event(struct uvc_device *dev)
> +{
> + struct uvc_entity *unit = dev->gpio_unit;
> + struct uvc_video_chain *chain;
> + u8 new_val;
> +
> + if (!unit)
> + return;
> +
> + new_val = gpiod_get_value_cansleep(unit->gpio.gpio_privacy);
> +
> + /* GPIO entities are always on the first chain. */
> + chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
> + uvc_ctrl_status_event(chain, unit->controls, &new_val);
> +}
> +
> +static int uvc_gpio_get_cur(struct uvc_device *dev, struct uvc_entity *entity,
> + u8 cs, void *data, u16 size)
> +{
> + if (cs != UVC_CT_PRIVACY_CONTROL || size < 1)
> + return -EINVAL;
> +
> + *(u8 *)data = gpiod_get_value_cansleep(entity->gpio.gpio_privacy);
> +
> + return 0;
> +}
> +
> +static int uvc_gpio_get_info(struct uvc_device *dev, struct uvc_entity *entity,
> + u8 cs, u8 *caps)
> +{
> + if (cs != UVC_CT_PRIVACY_CONTROL)
> + return -EINVAL;
> +
> + *caps = UVC_CONTROL_CAP_GET | UVC_CONTROL_CAP_AUTOUPDATE;
> + return 0;
> +}
> +
> +static irqreturn_t uvc_gpio_irq(int irq, void *data)
> +{
> + struct uvc_device *dev = data;
> +
> + uvc_gpio_event(dev);
> + return IRQ_HANDLED;
> +}
> +
> +static int uvc_gpio_parse(struct uvc_device *dev)
> +{
> + struct uvc_entity *unit;
> + struct gpio_desc *gpio_privacy;
> + int irq;
> +
> + gpio_privacy = devm_gpiod_get_optional(&dev->udev->dev, "privacy",
> + GPIOD_IN);
> + if (IS_ERR_OR_NULL(gpio_privacy))
> + return PTR_ERR_OR_ZERO(gpio_privacy);
> +
> + unit = uvc_alloc_entity(UVC_EXT_GPIO_UNIT, UVC_EXT_GPIO_UNIT_ID, 0, 1);
> + if (!unit)
> + return -ENOMEM;
> +
> + irq = gpiod_to_irq(gpio_privacy);
> + if (irq < 0) {
> + if (irq != EPROBE_DEFER)
> + dev_err(&dev->udev->dev,
> + "No IRQ for privacy GPIO (%d)\n", irq);
> + return irq;
> + }
> +
> + unit->gpio.gpio_privacy = gpio_privacy;
> + unit->gpio.irq = irq;
> + unit->gpio.bControlSize = 1;
> + unit->gpio.bmControls = (u8 *)unit + sizeof(*unit);
> + unit->gpio.bmControls[0] = 1;
> + unit->get_cur = uvc_gpio_get_cur;
> + unit->get_info = uvc_gpio_get_info;
> + strncpy(unit->name, "GPIO", sizeof(unit->name) - 1);
> +
> + list_add_tail(&unit->list, &dev->entities);
> +
> + dev->gpio_unit = unit;
> +
> + return 0;
> +}
> +
> +static int uvc_gpio_init_irq(struct uvc_device *dev)
> +{
> + struct uvc_entity *unit = dev->gpio_unit;
> +
> + if (!unit || unit->gpio.irq < 0)
> + return 0;
> +
> + return devm_request_threaded_irq(&dev->udev->dev, unit->gpio.irq, NULL,
> + uvc_gpio_irq,
> + IRQF_ONESHOT | IRQF_TRIGGER_FALLING |
> + IRQF_TRIGGER_RISING,
> + "uvc_privacy_gpio", dev);
> +}
> +
> /* ------------------------------------------------------------------------
> * UVC device scan
> */
> @@ -1988,6 +2095,13 @@ static int uvc_scan_device(struct uvc_device *dev)
> return -1;
> }
>
> + /* Add GPIO entity to the first chain. */
> + if (dev->gpio_unit) {
> + chain = list_first_entry(&dev->chains,
> + struct uvc_video_chain, list);
> + list_add_tail(&dev->gpio_unit->chain, &chain->entities);
> + }
> +
> return 0;
> }
>
> @@ -2350,6 +2464,12 @@ static int uvc_probe(struct usb_interface *intf,
> goto error;
> }
>
> + /* Parse the associated GPIOs. */
> + if (uvc_gpio_parse(dev) < 0) {
> + uvc_trace(UVC_TRACE_PROBE, "Unable to parse UVC GPIOs\n");
> + goto error;
> + }
> +
> uvc_printk(KERN_INFO, "Found UVC %u.%02x device %s (%04x:%04x)\n",
> dev->uvc_version >> 8, dev->uvc_version & 0xff,
> udev->product ? udev->product : "<unnamed>",
> @@ -2394,6 +2514,13 @@ static int uvc_probe(struct usb_interface *intf,
> "supported.\n", ret);
> }
>
> + ret = uvc_gpio_init_irq(dev);
> + if (ret < 0) {
> + dev_err(&dev->udev->dev,
> + "Unable to request privacy GPIO IRQ (%d)\n", ret);
> + goto error;
> + }
> +
> uvc_trace(UVC_TRACE_PROBE, "UVC device initialized.\n");
> usb_enable_autosuspend(udev);
> return 0;
> diff --git a/drivers/media/usb/uvc/uvc_entity.c b/drivers/media/usb/uvc/uvc_entity.c
> index 7c9895377118c..96e965a16d061 100644
> --- a/drivers/media/usb/uvc/uvc_entity.c
> +++ b/drivers/media/usb/uvc/uvc_entity.c
> @@ -105,6 +105,7 @@ static int uvc_mc_init_entity(struct uvc_video_chain *chain,
> case UVC_OTT_DISPLAY:
> case UVC_OTT_MEDIA_TRANSPORT_OUTPUT:
> case UVC_EXTERNAL_VENDOR_SPECIFIC:
> + case UVC_EXT_GPIO_UNIT:
> default:
> function = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
> break;
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 0e4209dbf307f..e9eef2170d866 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -6,6 +6,7 @@
> #error "The uvcvideo.h header is deprecated, use linux/uvcvideo.h instead."
> #endif /* __KERNEL__ */
>
> +#include <linux/atomic.h>
> #include <linux/kernel.h>
> #include <linux/poll.h>
> #include <linux/usb.h>
> @@ -37,6 +38,8 @@
> (UVC_ENTITY_IS_TERM(entity) && \
> ((entity)->type & 0x8000) == UVC_TERM_OUTPUT)
>
> +#define UVC_EXT_GPIO_UNIT 0x7ffe
> +#define UVC_EXT_GPIO_UNIT_ID 0x100
>
> /* ------------------------------------------------------------------------
> * GUIDs
> @@ -56,6 +59,9 @@
> #define UVC_GUID_UVC_SELECTOR \
> {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
> 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02}
> +#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_FORMAT_MJPEG \
> { 'M', 'J', 'P', 'G', 0x00, 0x00, 0x10, 0x00, \
> @@ -213,6 +219,7 @@
> * Structures.
> */
>
> +struct gpio_desc;
> struct uvc_device;
>
> /* TODO: Put the most frequently accessed fields at the beginning of
> @@ -354,6 +361,13 @@ struct uvc_entity {
> u8 *bmControls;
> u8 *bmControlsType;
> } extension;
> +
> + struct {
> + u8 bControlSize;
> + u8 *bmControls;
> + struct gpio_desc *gpio_privacy;
> + int irq;
> + } gpio;
> };
>
> u8 bNrInPins;
> @@ -696,6 +710,8 @@ struct uvc_device {
> struct uvc_control *ctrl;
> const void *data;
> } async_ctrl;
> +
> + struct uvc_entity *gpio_unit;
> };
>
> enum uvc_handle_state {

--
Ben Hutchings
When in doubt, use brute force. - Ken Thompson

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