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

Ricardo Ribalda
2026-04-13T20:50:45Z

On Mon, 13 Apr 2026 at 22:43, Ben Hutchings <ben@decadent.org.uk> wrote:
>
> 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.

Agree with Ben here.

if the reason for this patch is to get "media: uvcvideo: Use
heuristic to find stream entity" in 5.10 I can work on a backport that
only adds this feature without GPIO it should be pretty easy.

>
> 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

--
Ricardo Ribalda