On Tue, 9 Feb 2010, Guennadi Liakhovetski wrote: > On Tue, 9 Feb 2010, Alan Stern wrote: > > > On Mon, 8 Feb 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. > > > > > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> > > > --- > > > > > > I've posted this patch to linux-media earlier, but I'd also like to get > > > comments on linux-pm, sorry to linux-media falks for a duplicate. To > > > explain a bit - soc_camera.c is a management module, that binds video > > > interfaces on SoCs and sensor drivers. The calls, that I am adding to > > > soc_camera.c shall save and restore sensor registers before they are > > > powered down and after they are powered up. > > > > This patch is not correct as it stands. If you use runtime PM then the > > system PM resume method has to be changed. See the discussion in > > section 6 of Documentation/power/runtime_pm.txt. > > ...changed - for the same device, right? And I don't see any system PM > methods implemented for these devices yet. Oh, if these new routines are just bus glue then you're right, it doesn't matter. The changes would have to be made in the lower-level drivers, when they implement runtime PM. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
