linux-kernel - [PATCH v3 0/6] media: uvcvideo: Implement Granular Power Saving

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Message-Id: <20250206-uvc-granpower-ng-v3-0-32d0d7b0c5d8@chromium.org>
Date: Thu, 06 Feb 2025 19:46:59 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Hans de Goede <hdegoede@...hat.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Guennadi Liakhovetski <guennadi.liakhovetski@...el.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Mauro Carvalho Chehab <mchehab+samsung@...nel.org>, 
 Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH v3 0/6] media: uvcvideo: Implement Granular Power Saving

Right now we power-up the device when a user open() the device and we
power it off when the last user close() the first video node.

This behaviour affects the power consumption of the device is multiple
use cases, such as:
- Polling the privacy gpio
- udev probing the device

This patchset introduces a more granular power saving behaviour where
the camera is only awaken when needed. It is compatible with
asynchronous controls.

While developing this patchset, two bugs were found. The patchset has
been developed so these fixes can be taken independently.

Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
Changes in v3:
- Fix build error on sh4.
- Link to v2: https://lore.kernel.org/r/20250203-uvc-granpower-ng-v2-0-bef4b55e7b67@chromium.org

Changes in v2:
- Add missing semicolon.
- Rebase on top of media-committers/next
- Link to v1: https://lore.kernel.org/r/20241126-uvc-granpower-ng-v1-0-6312bf26549c@chromium.org

---
Ricardo Ribalda (6):
      media: uvcvideo: Keep streaming state in the file handle
      media: uvcvideo: Move usb_autopm_(get|put)_interface to status_get
      media: uvcvideo: Add a uvc_status guard
      media: uvcvideo: Increase/decrease the PM counter per IOCTL
      media: uvcvideo: Make power management granular
      media: uvcvideo: Do not turn on the camera for some ioctls

 drivers/media/usb/uvc/uvc_ctrl.c   | 13 ++++++-
 drivers/media/usb/uvc/uvc_status.c | 38 ++++++++++++++++---
 drivers/media/usb/uvc/uvc_v4l2.c   | 76 ++++++++++++++++++++++++++------------
 drivers/media/usb/uvc/uvcvideo.h   |  3 ++
 4 files changed, 100 insertions(+), 30 deletions(-)
---
base-commit: 39e3f5bc0ab4a86b0c8fcda0688d21651ec17242
change-id: 20241126-uvc-granpower-ng-069185a6d474

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