On Mon, 8 Feb 2010, Mauro Carvalho Chehab wrote:
> In fact, on all drivers, there are devices that needs to be turn on only when
> streaming is happening: sensors, analog TV/audio demods, digital demods. Also,
> a few devices (for example: TV tuners) could eventually be on power off when
> no device is opened.
>
> As the V4L core knows when this is happening (due to
> open/close/poll/streamon/reqbuf/qbuf/dqbuf hooks, I think the runtime
> management
> can happen at V4L core level.
Well, we can move it up to v4l core. Should it get any more complicated
than adding
ret = pm_runtime_resume(&vdev->dev);
if (ret < 0 && ret != -ENOSYS)
return ret;
to v4l2_open() and
pm_runtime_suspend(&vdev->dev);
to v4l2_release()? And to agree, that video drivers may set a device type
to implement runtime PM, and that the v4l core shouldn't touch it? Then,
for example, a bridge driver could implement such a device type instance
and suspend or resume all related components?
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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