linux-kernel - [PATCH v3 0/7] [RESEND] media: uvcvideo: Implement granular power management

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Message-Id: <20220920-resend-powersave-v3-0-c47856d8757e@chromium.org>
Date:   Wed, 26 Oct 2022 14:06:05 +0200
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Tomasz Figa <tfiga@...omium.org>,
        Ricardo Ribalda <ribalda@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Max Staudt <mstaudt@...omium.org>,
        linux-kernel@...r.kernel.org,
        Alan Stern <stern@...land.harvard.edu>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        linux-media@...r.kernel.org
Subject: [PATCH v3 0/7] [RESEND] media: uvcvideo: Implement granular power management

Instead of suspending/resume the USB device at open()/close(), do it
when the device is actually used.

This way we can reduce the power consumption when a service is holding
the video device and leaving it in an idle state.

And now that all the access to the hardware, has a common entry path,
use it to fix the race conditions to hardware disconnects.

To: Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Tomasz Figa <tfiga@...omium.org>
Cc: Alan Stern <stern@...land.harvard.edu>
Cc: Hans Verkuil <hverkuil-cisco@...all.nl>
Cc: Guenter Roeck <linux@...ck-us.net>
Cc: Max Staudt <mstaudt@...omium.org>
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
Changes in v3:
- Rebase on top of uvc/next
- Reorder series, and put "controversial" patches at the end.
- Fix "use-before-set" bug. Thanks Max!
- Link to v2: https://lore.kernel.org/r/20220920-resend-powersave-v2-0-5135d1bb1c38@chromium.org

Changes in v2:
- Make access to uvc_status contitional
- Merge with Guenter race condition patchset: https://lore.kernel.org/lkml/20200917022547.198090-1-linux@roeck-us.net/
- Link to v1: https://lore.kernel.org/r/20220920-resend-powersave-v1-0-123aa2ba3836@chromium.org

---
Guenter Roeck (4):
      media: uvcvideo: Cancel async worker earlier
      media: uvcvideo: Release stream queue when unregistering video device
      media: uvcvideo: Lock video streams and queues while unregistering
      media: uvcvideo: Protect uvc queue file operations against disconnect

Ricardo Ribalda (3):
      media: uvcvideo: Refactor streamon/streamoff
      media: uvcvideo: Do power management granularly
      media: uvcvideo: Only call status ep if hw supports it

 drivers/media/usb/uvc/uvc_ctrl.c   |  11 +-
 drivers/media/usb/uvc/uvc_driver.c |  35 +++++--
 drivers/media/usb/uvc/uvc_queue.c  |  32 +++++-
 drivers/media/usb/uvc/uvc_status.c |  11 +-
 drivers/media/usb/uvc/uvc_v4l2.c   | 206 ++++++++++++++++++++++++++++++-------
 drivers/media/usb/uvc/uvcvideo.h   |   2 +
 6 files changed, 248 insertions(+), 49 deletions(-)
---
base-commit: 58540610e464d8b2ba46a11b81c3e6fcc4118fae
change-id: 20220920-resend-powersave-5981719ed267

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