On Tue, 9 Feb 2010, Hans Verkuil wrote: > 1) is someone using the driver (i.e. is a device node open, which is not > necessarily limited to v4l2-type device nodes)? > 2) are we actively streaming from or to some particular input or output? > > And we probably need some easy way to detect and set the powersaving state > for each component (subdev or the main v4l2_device). > > I really need to research the pm stuff... That certainly wouldn't hurt, but I have to resolve a problem of a failing device now. And I have 3 options: 1. implement runtime_pm in soc-camera and down, using vdev->dev.type. Easy and relatively painless - we already have use-counts there, so, first open and last close are readily available. 2. add the same as above to v4l2-dev.c - wouldn't really want to do that, implications too large, no use-counting. 3. accept the patch from Val and just write registers, we are currently losing, on each s_fmt. Easy, but not very efficient - there can be other similar problems elsewhere... Which of them shall I do for now? Besides, I realise, that decisions which devices and when to suspend and to wake up are difficult, so, PM requires careful implementation. But doesn't this also mean, that we anyway cannot implement any specifics in the top level, and can only implement hooks to call hardware-specific pm callbacks, so, probably, the bridge driver will have to implement specifics anyway? Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- 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
