On Wed, Oct 06, 2010 at 02:19:03PM -0400, Alan Stern wrote: > On Wed, 6 Oct 2010, Dmitry Torokhov wrote: > > > > > I think last time Rafael mentioned that runtime PM did not allow for > > > > forcing power state from userspace but I wonder if it would be possible > > > > for userspace to signal and "accelerate" the idle state for a device and > > > > then standard runtime PM framework would kick in... > > > > > > Yes; drivers can implement their runtime power policy any way they > > > want. For example, a driver could create a sysfs attribute file which > > > userspace could use to ask for changes in the power state. > > > > > > The real question is whether the driver is platform-specific. If it is > > > then fine, it can do whatever it wants. If it isn't then it should > > > try to avoid doing things that are tied to a specific platform. > > > > > > > No, I really think it is wrong. This what leads us to the situation we > > are in at the moment. Every device [re]implements its own little knobs > > to do power management. Accelerometers export their (often tailored to a > > specific platform) attributes in sysfs in nonstandard way. And so on, > > and so forth. > > > > Here I'd like to see these (PM) hooks done on device core level, i.e. > > the knobs should be unified and live in /sys/devices/.../deviceX/power/ > > I haven't followed this thread in detail. What sort of knobs are you > talking about? That is, what needs to be done? Maybe the PM core > already provides these features. > Mobile folks wish to power down some devices (most often input - touchscreen, keypad) under certain circumstances to save power. So far they were doing that by adding "disable" hook to individual drivers and while I did allow that in for some devices I feel that we need more standardised solution, preferably one that could re-use existing PM hooks in drivers. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
