> -----Original Message-----
> From: [email protected] [mailto:linux-omap-
> [email protected]] On Behalf Of Premi, Sanjeev
> Sent: Monday, March 02, 2009 1:31 AM
> To: Dasgupta, Romit; Woodruff, Richard; [email protected]
> Subject: RE: omap3 cpuidle interrupt latency
>
> > -----Original Message-----
> > From: Dasgupta, Romit
> > Sent: Sunday, March 01, 2009 12:18 PM
> > To: Woodruff, Richard; Premi, Sanjeev; [email protected]
> > Subject: RE: omap3 cpuidle interrupt latency
> >
> > It would be nice if this device could dynamically set
> > constraints (say by using a short kernel timer during
> > activity or set/remove pm_qos latency) or the prediction
> > aspect of cpuidle could be improved using rules feed from
> > things like interrupt source.
>
> Despite all constraints; the latency concern is still valid.
>
> The constraints would either prevent idle state transition;
> or in the idle processing we could still have repeat of current
> situation - though less often.
>
> I feel checking for pending interrupt before executing WFI
> would help. Will try in the morning.
Moving time keeping functions out of interrupt disabled context may also help.
Something like this
return_sleep_time:
local_irq_enable();
local_fiq_enable();
getnstimeofday(&ts_postidle);
ts_idle = timespec_sub(ts_postidle, ts_preidle);
ARM will wakeup from WFI idle on nIRQ/nFIQ signal assertion. But interrupts
will be processed only after they are enabled in CPSR AFAIK.
Regards,
Pratheesh
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