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SubjectRe: [linux-pm] [PATCH 1/8] PM: Add suspend block api.
2010/5/3 mark gross <>:
> On Fri, Apr 30, 2010 at 03:36:54PM -0700, Arve Hjønnevåg wrote:
>> +When the policy is "opportunisic", there is a special value, "on", that can be
>> +written to /sys/power/state. This will block the automatic sleep request, as if
>> +a suspend blocker was used by a device driver. This way the opportunistic
>> +suspend may be blocked by user space whithout switching back to the "forced"
>> +mode.
> You know things would be so much easier if the policy was a one-shot
> styled thing.  i.e. when enabled it does what it does, but upon resume
> the policy must be re-enabled by user mode to get the opportunistic
> behavior.  That way we don't need to grab the suspend blocker from the
> wake up irq handler all the way up to user mode as the example below
> calls out.  I suppose doing this would put a burden on the user mode code
> to keep track of if it has no pending blockers registered after a wake
> up from the suspend.  but that seems nicer to me than sprinkling
> overlapping blocker critical sections from the mettle up to user mode.
> Please consider making the policy a one shot API that needs to be
> re-enabled after resume by user mode.  That would remove my issue with
> the design.

Making it one shot does not change where kernel code needs to block
suspend, but it does force user space to poll trying to suspend while
suspend is blocked by a driver.

Arve Hjønnevåg
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