Re: [PATCH/RESEND] soc-camera: add runtime pm support for subdevices

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On Mon, 8 Feb 2010, Rafael J. Wysocki wrote:

> On Monday 08 February 2010, Guennadi Liakhovetski wrote:
> > To save power soc-camera powers subdevices down, when they are not in use, 
> > if this is supported by the platform. However, the V4L standard dictates, 
> > that video nodes shall preserve configuration between uses. This requires 
> > runtime power management, which is implemented by this patch. It allows 
> > subdevice drivers to specify their runtime power-management methods, by 
> > assigning a type to the video device.
> 
> You need a support for that at the bus type/device type/device class level,
> because the core doesn't execute the driver callbacks directly.

That's exactly what this patch is doing - adding a device type with pm 
callbacks. What I wasn't sure about - and why I posted here - is whether 
that's a proper way to use pm_runtime_resume() and pm_runtime_suspend() 
calls - from a central module, targeting underlying devices, before 
powering them down and after powering them up?

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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