Messages in this thread | | | From | "Shilimkar, Santosh" <> | Date | Tue, 10 Apr 2012 12:26:43 +0530 | Subject | Re: [PATCH] clockevents: Leave broadcast device shtudown only if the current device is always running. |
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On Tue, Apr 10, 2012 at 4:11 AM, Suresh Siddha <suresh.b.siddha@intel.com> wrote: > On Mon, 2012-04-09 at 11:33 +0530, Santosh Shilimkar wrote: >> Commit 77b0d60{clockevents: Leave the broadcast device in shutdown mode >> when not needed} was intended to leave the broadcast device in shutdown mode >> when the per-cpu clockevent devices are always running. >> >> This breaks the systems where per cpu clock events stop in low power states. >> >> Hence revert 77b0d60 and implement the same requirement with use >> of C3STOP feature flag. > > Problem you encountered is not related to leaving the broadcast device > in shutdown mode. Problem is that we didn't track the mode change to > oneshot and later during idle entry/exit, when we request the broadcast > device services using CLOCK_EVT_NOTIFY_BROADCAST_ENTER etc, > tick_broadcast_oneshot_control() returns with out doing much as it > thinks broadcast device is in periodic mode. > You are right. In my last traces I didn't track the broadcast device state fully. Did some more tracing and indeed the issue was the broadcast device mode.
> Can you please check if the appended patch fixes the issue? I could > reproduce the issue on my NHM platform which doesn't have always running > apic timer and with the appended fix, all is well with cpu's going into > tickless idle etc. Thanks. > --- > Yes it does work on OMAP too.
> From: Suresh Siddha <suresh.b.siddha@intel.com> > Subject: clockevents: track broadcast device mode change in tick_broadcast_switch_to_oneshot() > > In the commit 77b0d60c5adf39c74039e2142a1d3cd1e4d53799, > "clockevents: Leave the broadcast device in shutdown mode when not needed", > we were bailing out too quickly in tick_broadcast_switch_to_oneshot(), > with out tracking the broadcast device mode change to 'TICKDEV_MODE_ONESHOT'. > > This breaks the platforms which need broadcast device oneshot services during > deep idle states. tick_broadcast_oneshot_control() thinks that it is > in periodic mode and fails to take proper decisions based on the > CLOCK_EVT_NOTIFY_BROADCAST_[ENTER, EXIT] notifications during deep > idle entry/exit. > > Fix this by tracking the broadcast device mode as 'TICKDEV_MODE_ONESHOT', > before leaving the broadcast HW device in shutdown mode if there are no active > requests for the moment. > > Reported-by: Santosh Shilimkar <santosh.shilimkar@ti.com> > Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> > --- Thanks for the patch. Feel free to add, Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Regards Santosh
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