Re: [RFD] Automatic suspend

Arve Hjønnevåg
2009-02-24T00:02:42Z

On Mon, Feb 23, 2009 at 3:53 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> On Tuesday 24 February 2009, Arve Hjønnevåg wrote:
>> On Sat, Feb 21, 2009 at 12:20 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> > On Saturday 21 February 2009, Arve Hjønnevåg wrote:
>> >> On Sat, Feb 21, 2009 at 1:47 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> >> > On Saturday 21 February 2009, Arve Hjønnevåg wrote:
>> >> >> On Fri, Feb 20, 2009 at 3:57 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> >> >> > On Saturday 21 February 2009, Arve Hjønnevåg wrote:
>> >> >> >> On Fri, Feb 20, 2009 at 7:56 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> >> >> >> > On Friday 20 February 2009, Arve Hjønnevåg wrote:
>> >> >> >> >> On Fri, Feb 20, 2009 at 2:49 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> >> >> >> >> > On Friday 20 February 2009, Arve Hjønnevåg wrote:
>> >> >> >> >> >> On Thu, Feb 19, 2009 at 2:08 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
>> > [--snip--]
>> >> >> > The idea is to have both /sys/power/state and /sys/power/sleep at the same
>> >> >> > time, where /sys/power/state will work just like it does right now. Sure,
>> >> >> > there must be mutual exclusion between the two, but that's a matter of
>> >> >> > implementation IMO.
>> >> >>
>> >> >> If you want to only prevent suspend though one interface, you have to
>> >> >> also pass information to the driver about its suspend hook is being
>> >> >> called so it can conditionally return -EBUSY. The wakelock interface
>> >> >> requires less code in each driver.
>> >> >
>> >> > Well, I don't think so. Moreover, it requires you to spread wakelocks all
>> >> > over the place if you don't use the timeouted ones which, let's face it, is
>> >> > hardly acceptable.
>> >>
>> >> Your method does not reduce the number of places that has to be
>> >> modified. Any component where we add a wakelock, you have to add a
>> >> suspend handler to abort suspend when we would have held a wakelock.
>> >
>> > Well, maybe not, but it doesn't introduce entirely new API for device drivers.
>> > Instead, it extends the existing interfaces which I think is more appropriate.
>>
>> The existing interfaces require polling. I don't think extending these
>> interfaces to make the polling faster is a better solution than adding
>> an interface to avoid polling.
>>
>> Also, with your solution, how would you modify evdev.c to prevent
>> suspend while the event queue is not empty. This code does not have
>> any suspend hooks and the queue is not tied to any thread.
>
> Well, why do you need to modify evdev.c in the first place?

It is the only code that knows that there are unprocessed input events.

--
Arve Hjønnevåg