Some notebooks have a button to disable the camera (not to be mistaken with the mechanical cover). This is a standard GPIO linked to the camera via the ACPI table. 4 years ago we added support for this button in UVC via the Privacy control. This has two issues: - If the camera has its own privacy control, it will be masked - We need to power-up the camera to read the privacy control gpio. We tried to fix the power-up issues implementing "granular power saving" but it has been more complicated than anticipated.... Last year, we proposed a patchset to implement the privacy gpio as a subdevice https://lore.kernel.org/linux-media/20230111-uvc_privacy_subdev-v1-0-f859ac9a01e3@xxxxxxxxxxxx/ I think it is a pretty clean solution and makes sense to use a subdevice for something that is a sub device of the camera :). This is an attempt to continue with that approach. Tested on gimble: gimble-rev3 ~ # v4l2-ctl --all -d /dev/v4l-subdev0 Driver Info: Driver version : 6.6.56 Capabilities : 0x00000000 Media Driver Info: Driver name : uvcvideo Model : HP 5M Camera: HP 5M Camera Serial : 0001 Bus info : usb-0000:00:14.0-6 Media version : 6.6.56 Hardware revision: 0x00009601 (38401) Driver version : 6.6.56 Interface Info: ID : 0x0300001d Type : V4L Sub-Device Entity Info: ID : 0x00000013 (19) Name : GPIO Function : Analog Video Decoder Camera Controls privacy 0x009a0910 (bool) : default=0 value=0 flags=read-only, volatile gimble-rev3 ~ # media-ctl -p Media controller API version 6.6.56 Media device information ------------------------ driver uvcvideo model HP 5M Camera: HP 5M Camera serial 0001 bus info usb-0000:00:14.0-6 hw revision 0x9601 driver version 6.6.56 Device topology - entity 1: HP 5M Camera: HP 5M Camera (1 pad, 1 link) type Node subtype V4L flags 1 device node name /dev/video0 pad0: Sink <- "Extension 8":1 [ENABLED,IMMUTABLE] - entity 4: HP 5M Camera: HP 5M Camera (0 pad, 0 link) type Node subtype V4L flags 0 device node name /dev/video1 - entity 8: Extension 8 (2 pads, 2 links, 0 routes) type V4L2 subdev subtype Unknown flags 0 pad0: Sink <- "Extension 4":1 [ENABLED,IMMUTABLE] pad1: Source -> "HP 5M Camera: HP 5M Camera":0 [ENABLED,IMMUTABLE] - entity 11: Extension 4 (2 pads, 2 links, 0 routes) type V4L2 subdev subtype Unknown flags 0 pad0: Sink <- "Processing 2":1 [ENABLED,IMMUTABLE] pad1: Source -> "Extension 8":0 [ENABLED,IMMUTABLE] - entity 14: Processing 2 (2 pads, 2 links, 0 routes) type V4L2 subdev subtype Unknown flags 0 pad0: Sink <- "Camera 1":0 [ENABLED,IMMUTABLE] pad1: Source -> "Extension 4":0 [ENABLED,IMMUTABLE] - entity 17: Camera 1 (1 pad, 1 link, 0 routes) type V4L2 subdev subtype Sensor flags 0 pad0: Source -> "Processing 2":0 [ENABLED,IMMUTABLE] - entity 19: GPIO (0 pad, 0 link, 0 routes) type V4L2 subdev subtype Decoder flags 0 device node name /dev/v4l-subdev0 Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> --- Ricardo Ribalda (6): media: uvcvideo: Factor out gpio functions to its own file Revert "media: uvcvideo: Allow entity-defined get_info and get_cur" media: uvcvideo: Create ancillary link for GPIO subdevice media: v4l2-core: Add new MEDIA_ENT_F_GPIO media: uvcvideo: Use MEDIA_ENT_F_GPIO for the GPIO entity media: uvcvideo: Introduce UVC_QUIRK_PRIVACY_DURING_STREAM Yunke Cao (1): media: uvcvideo: reimplement privacy GPIO as a separate subdevice .../userspace-api/media/mediactl/media-types.rst | 4 + drivers/media/usb/uvc/Makefile | 3 +- drivers/media/usb/uvc/uvc_ctrl.c | 40 +---- drivers/media/usb/uvc/uvc_driver.c | 112 +------------ drivers/media/usb/uvc/uvc_entity.c | 20 ++- drivers/media/usb/uvc/uvc_gpio.c | 178 +++++++++++++++++++++ drivers/media/usb/uvc/uvc_video.c | 4 + drivers/media/usb/uvc/uvcvideo.h | 31 ++-- drivers/media/v4l2-core/v4l2-async.c | 3 +- include/uapi/linux/media.h | 1 + 10 files changed, 242 insertions(+), 154 deletions(-) --- base-commit: c7ccf3683ac9746b263b0502255f5ce47f64fe0a change-id: 20241030-uvc-subdev-89f4467a00b5 Best regards, -- Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
