On Út 27-12-05 11:29:56, Patrick Mochel wrote: > On Tue, Dec 27, 2005 at 08:22:54PM +0100, Pavel Machek wrote: > > > I don't really think we want complexity of putting PCI device into > > D0/D1/D2/D3hot/D3cold. All that userspace should care about is device > > working/device suspended, and we could not test all 5 states, anyway. > > What do you mean? > > The devices and drivers should support various states, and that's the > whole point of having multiple states - to make a choice based on the > power saving required vs. the latency requirements of bringing it back. > > Granted, for most things, the latency to return from D3 (hot only, cold > is irrelevant during runtime) is not going to be noticable, so that's > probably the only state most devices will ever enter. Exactly. And for these "most devices", having to test/debug/support D1/D2 is not worth the effort. > But, in some cases, peple are going to care about the intermediate > states, and we'll need to support them. It's simple enought to know > what states a PCI device supports, so I don't understand where the > complexity comes in.. ? Someone has to test all that... Unless we have in-tree driver that wants use intermediate states, I think supporting them is bad idea. Pavel -- Thanks, Sharp!
