On 05/14/2014 09:50 PM, Santosh Shilimkar wrote:
On Wednesday 14 May 2014 03:44 PM, Daniel Lezcano wrote:
On 05/13/2014 04:39 PM, Santosh Shilimkar wrote:
On OMAP4 panda board, there have been several bug reports about boot
hang and lock-ups with CPU_IDLE enabled. The root cause of the issue
is missing interrupts while in idle state. Commit cb7094e8 {cpuidle / omap4 :
use CPUIDLE_FLAG_TIMER_STOP flag} moved the broadcast notifiers to common
code for right reasons but on OMAP4 which suffers from a nasty ROM code
bug with GIC, commit ff999b8a {ARM: OMAP4460: Workaround for ROM bug ..},
we loose interrupts which leads to issues like lock-up, hangs etc.
Patch reverts commit cb7094 {cpuidle / omap4 : use CPUIDLE_FLAG_TIMER_STOP
flag} to avoid the issue. With this change, OMAP4 panda boards, the mentioned
issues are getting fixed. We no longer loose interrupts which was the cause
of the regression.
Cc: Roger Quadros <[email protected]>
Cc: Kevin Hilman <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Reported-tested-by: Roger Quadros <[email protected]>
Reported-tested-by: Kevin Hilman <[email protected]>
Tested-by: Tony Lindgren <[email protected]>
Signed-off-by: Santosh Shilimkar <[email protected]>
---
[ ... ]
+ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu_id);
+
/*
* Call idle CPU PM enter notifier chain so that
* VFP and per CPU interrupt context is saved.
@@ -165,6 +169,8 @@ static int omap_enter_idle_coupled(struct cpuidle_device
*dev,
if (dev->cpu == 0 && mpuss_can_lose_context)
cpu_cluster_pm_exit();
+ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu_id);
[ ... ]
Shouldn't the broadcast timer to be setup with CLOCK_EVT_NOTIFY_BROADCAST_ON
also ?
Which is already taken care by __cpuidle_register_driver(). Note that setup code
is still used from generic code...
Nope, if the flag CPUIDLE_FLAG_TIMER_STOP is not set, the cpuidle
framework won't setup the timer.
static void __cpuidle_driver_init(struct cpuidle_driver *drv)
{
...
for (i = drv->state_count - 1; i >= 0 ; i--) {
if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) {
drv->bctimer = 1;
break;
}
}
...
}
static int __cpuidle_register_driver(struct cpuidle_driver *drv)
{
...
if (drv->bctimer)
on_each_cpu_mask(drv->cpumask,
cpuidle_setup_broadcast_timer,
(void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, 1);
...
}
So the broadcast timer does not operate with this revert. Moreover, I am
not sure reverting this patch is the right solution.
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