[PATCH v2 0/6] media: uvcvideo: Implement the Privacy GPIO as a subdevice

Ricardo Ribalda
2024-11-08T20:25:49Z

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@chromium.org/

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 : Unknown sub-device (00020006)

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@chromium.org>
---
Changes in v2:
- Rebase on top of https://patchwork.linuxtv.org/project/linux-media/patch/20241106-uvc-crashrmmod-v6-1-fbf9781c6e83@chromium.org/
- Create uvc_gpio_cleanup and uvc_gpio_deinit
- Refactor quirk: do not disable irq
- Change define number for MEDIA_ENT_F_GPIO
- Link to v1: https://lore.kernel.org/r/20241031-uvc-subdev-v1-0-a68331cedd72@chromium.org

---
Ricardo Ribalda (5):
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

Yunke Cao (1):
media: uvcvideo: Re-implement 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 | 123 +-------------
drivers/media/usb/uvc/uvc_entity.c | 20 ++-
drivers/media/usb/uvc/uvc_gpio.c | 187 +++++++++++++++++++++
drivers/media/usb/uvc/uvc_video.c | 4 +
drivers/media/usb/uvc/uvcvideo.h | 34 ++--
drivers/media/v4l2-core/v4l2-async.c | 3 +-
include/uapi/linux/media.h | 1 +
10 files changed, 252 insertions(+), 167 deletions(-)
---
base-commit: 4353256f5487e0c5c47e8ff764bf4f9e679fb525
change-id: 20241030-uvc-subdev-89f4467a00b5

Best regards,
--
Ricardo Ribalda <ribalda@chromium.org>