linux-kernel - [PATCH v5 0/2] media: uvcvideo: Implement granular power management

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Message-Id: <20220920-resend-powersave-v5-0-692e6df6c1e2@chromium.org>
Date:   Tue, 06 Dec 2022 15:06:54 +0100
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Tomasz Figa <tfiga@...omium.org>,
        Alan Stern <stern@...land.harvard.edu>,
        linux-kernel@...r.kernel.org, Max Staudt <mstaudt@...omium.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Yunke Cao <yunkec@...omium.org>,
        Ricardo Ribalda <ribalda@...omium.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        linux-media@...r.kernel.org
Subject: [PATCH v5 0/2] 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.

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>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Yunke Cao <yunkec@...omium.org>
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
Changes in v5:
- Improve uvc_fd padding (Thanks Sergey)
- Take the mutex always in the same order.
- Link to v4: https://lore.kernel.org/r/20220920-resend-powersave-v4-0-47484ae40761@chromium.org

Changes in v4:
- Remove patches to avoid crashes during device removal
- Link to v3: https://lore.kernel.org/r/20220920-resend-powersave-v3-0-c47856d8757e@chromium.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

---
Ricardo Ribalda (2):
      media: uvcvideo: Refactor streamon/streamoff
      media: uvcvideo: Do power management granularly

 drivers/media/usb/uvc/uvc_v4l2.c | 217 +++++++++++++++++++++++++++++++--------
 drivers/media/usb/uvc/uvcvideo.h |   1 +
 2 files changed, 178 insertions(+), 40 deletions(-)
---
base-commit: f599c56de2bfcf5ff791b0f4155e997e08e364f0
change-id: 20220920-resend-powersave-5981719ed267

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