[PATCH] ARM: tegra: cpuidle: use CPUIDLE_FLAG_TIMER_STOP flag

[Joseph Lo]

On Wed, 2013-07-17 at 03:51 +0800, Stephen Warren wrote:
> On 07/16/2013 05:17 AM, Joseph Lo wrote:
> > On Tue, 2013-07-16 at 02:04 +0800, Stephen Warren wrote:
> >> On 06/25/2013 03:23 AM, Joseph Lo wrote:
> >>> Use the CPUIDLE_FLAG_TIMER_STOP and let the cpuidle framework
> >>> to handle the CLOCK_EVT_NOTIFY_BROADCAST_ENTER/EXIT when entering
> >>> this state.
> > or something can increase
> > the loading or make regressions. But I think you are testing with USB
> > device attached, right? That might cause some extra loading. You can
> > give it a try after just removing USB device. And I double confirm that
> > on Seaboard. Except that, the test result looks OK for me.
> 
> Yes, having a USB device plugged in does affect the issue. In summary:
> 
> next-20130716, with or without USB devices plugged in: Works fine.
> 
> next-20130716 with your patches, without USB device plugged in:
> Occasional short problems (detailed below).
> 
> next-20130716 with your patches, with USB device plugged in: Continual
> long problems (detailed below).
> 
> The testing I did was to log in over the serial console, hit <enter>
> around five times, and watch the shell prompt echo back, then type
> "ls<enter" and watch the (directory listing appear (I have about 20
> files in my directory, with long-ish names), then repeat. With plain
> next-20130716, this is nice and fast and there are no pauses. With your
> patches applied, there are occasional or continual pauses, which last
> for either a short time (tenths of a second), or even a second or two,
> both depending on whether a USB device is plugged in or not.
> 
> I believe this is the same issue I saw when I applied your patches to
> the Tegra tree on top of v3.11-rc1.
> 
OK. I did more stress tests last night and today. I found it cause by
the patch "ARM: tegra: cpuidle: use CPUIDLE_FLAG_TIMER_STOP flag" and
only impact the Tegra20 platform. The hot plug regression seems due to
this patch. After dropping this patch on top of v3.11-rc1, the Tegra20
can back to normal.

And the hop plug and suspend stress test can pass on Tegra30/114 too.

Can the other two patch series for Tegra114 to support CPU idle power
down mode and system suspend still moving forward, not be blocked by
this patch?

Looks the CPUIDLE_FLAG_TIMER_STOP flag still cause some other issue for
hot plug on Tegra20, I will continue to check this. You can just drop
this patch.

Thanks,
Joseph