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.
The ACPI table maps this GPIO to the USB device via _CRS and _DSD descriptors, so the kernel can find it. The userspace applications need to know if the privacy pin is enabled or not. The obvious way to show it to userspace is via the V4L2_CID_PRIVACY control. This patchset implement this functionality. Ricardo Ribalda (6): media: uvcvideo: Add UVC_CTRL_FLAG_ENTITY_GET_INFO media: uvcvideo: Add UVC_CTRL_FLAG_ENTITY_GET_CUR media: uvcvideo: Add UVC_GUID_EXT_GPIO_CONTROLLER media: uvcvideo: Add Privacy control based on EXT_GPIO media: uvcvideo: Implement UVC_GPIO_UNIT media: uvcvideo: Handle IRQs from the privacy_pin drivers/media/usb/uvc/uvc_ctrl.c | 56 ++++++++++++++-- drivers/media/usb/uvc/uvc_driver.c | 102 +++++++++++++++++++++++++++++ drivers/media/usb/uvc/uvcvideo.h | 14 ++++ include/uapi/linux/uvcvideo.h | 3 + 4 files changed, 169 insertions(+), 6 deletions(-) -- 2.29.0.rc1.297.gfa9743e501-goog