linux-kernel - Re: [PATCH 0/9] media: uvcvideo: Implement Granular Power Saving

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Message-ID: <42d06183-107e-4945-b83c-72be857c2067@redhat.com>
Date: Mon, 2 Dec 2024 13:10:27 +0100
From: Hans de Goede <hdegoede@...hat.com>
To: Ricardo Ribalda <ribalda@...omium.org>,
 Laurent Pinchart <laurent.pinchart@...asonboard.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>, stable@...r.kernel.org
Subject: Re: [PATCH 0/9] media: uvcvideo: Implement Granular Power Saving

Hi Ricardo,

On 26-Nov-24 5:18 PM, Ricardo Ribalda wrote:
> 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.

Thank you for your patch series. For now lets focus on fixing the
async-controls ctrl->handle setting / dangling ptr issue and then
we can look into the rest of this later (after we have also landed
the privacy GPIO and UVC 1.5 ROi series).

Regards,

Hans




> ---
> Ricardo Ribalda (9):
>       media: uvcvideo: Do not set an async control owned by other fh
>       media: uvcvideo: Remove dangling pointers
>       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
>       media: uvcvideo: Remove duplicated cap/out code
> 
>  drivers/media/usb/uvc/uvc_ctrl.c   |  52 +++++++++-
>  drivers/media/usb/uvc/uvc_status.c |  38 +++++++-
>  drivers/media/usb/uvc/uvc_v4l2.c   | 190 +++++++++++++++----------------------
>  drivers/media/usb/uvc/uvcvideo.h   |   6 ++
>  4 files changed, 166 insertions(+), 120 deletions(-)
> ---
> base-commit: 72ad4ff638047bbbdf3232178fea4bec1f429319
> change-id: 20241126-uvc-granpower-ng-069185a6d474
> 
> Best regards,