[PATCH] ARM: OMAP4: Fix the boot regression with CPU_IDLE enabled
Santosh Shilimkar
santosh.shilimkar at ti.com
Thu May 15 11:29:50 PDT 2014
On Thursday 15 May 2014 01:54 PM, Santosh Shilimkar wrote:
> On Thursday 15 May 2014 01:50 PM, Daniel Lezcano wrote:
>> On 05/15/2014 07:03 PM, Santosh Shilimkar wrote:
[..]
>>>> With above mentioned change, it should work. Other alternatives is OMAP4 driver does
>>>> its won registration where it can start the timer. The way it was before the
>>>> consolidation.
>>>>
>>>> Ofcourse if you have better fix, then great.
>>>>
>>> What is your suggestion. We *must* fix the regression asap. I think
>>> $subject patch with an update to bctimer start under CPUIDLE_FLAG_COUPLED
>>> seems a good way forward.
>>>
>>> Do let me know.
>>
>> Did you see Alex Shi's email [cc'ed] ? Reverting this change makes the panda ES to hang.
>>
> The hang is definitely due to the bctimer not started. As I said, I assumed it was and
> then you corrected saying it is under the flag.
>
>> I am not convinced the culprit is this code you are trying to revert.
>>
> fair enough. Thats why I said if you have an alternative fix thats great.
>
For record, below is updated patch with bctimer started which
was missed in earlier version. I haven't tested it though.
Alex,
Please give a try with your test-case and see if you still see the hang.
Am just curious about your issue and hence the request..
Regards,
Santosh
>From bb3b82cc5645b83bedf1343d03cc956f27f6fc83 Mon Sep 17 00:00:00 2001
From: Santosh Shilimkar <santosh.shilimkar at ti.com>
Date: Mon, 12 May 2014 17:37:59 -0400
Subject: [PATCH] ARM: OMAP4: Fix the boot regression with CPU_IDLE enabled
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} and 54769d6 {cpuidle: OMAP4: remove timer broadcast initialization} 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 <rogerq at ti.com>
Cc: Kevin Hilman <khilman at linaro.org>
Cc: Tony Lindgren <tony at atomide.com>
Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
Reported-tested-by: Roger Quadros <rogerq at ti.com>
Reported-tested-by: Kevin Hilman <khilman at linaro.org>
Tested-by: Tony Lindgren <tony at atomide.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
---
arch/arm/mach-omap2/cpuidle44xx.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)
diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c
index 01fc710..2498ab0 100644
--- a/arch/arm/mach-omap2/cpuidle44xx.c
+++ b/arch/arm/mach-omap2/cpuidle44xx.c
@@ -14,6 +14,7 @@
#include <linux/cpuidle.h>
#include <linux/cpu_pm.h>
#include <linux/export.h>
+#include <linux/clockchips.h>
#include <asm/cpuidle.h>
#include <asm/proc-fns.h>
@@ -83,6 +84,7 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev,
{
struct idle_statedata *cx = state_ptr + index;
u32 mpuss_can_lose_context = 0;
+ int cpu_id = smp_processor_id();
/*
* CPU0 has to wait and stay ON until CPU1 is OFF state.
@@ -110,6 +112,8 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev,
mpuss_can_lose_context = (cx->mpu_state == PWRDM_POWER_RET) &&
(cx->mpu_logic_state == PWRDM_POWER_OFF);
+ 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);
+
fail:
cpuidle_coupled_parallel_barrier(dev, &abort_barrier);
cpu_done[dev->cpu] = false;
@@ -172,6 +178,16 @@ fail:
return index;
}
+/*
+ * For each cpu, setup the broadcast timer because local timers
+ * stops for the states above C1.
+ */
+static void omap_setup_broadcast_timer(void *arg)
+{
+ int cpu = smp_processor_id();
+ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);
+}
+
static struct cpuidle_driver omap4_idle_driver = {
.name = "omap4_idle",
.owner = THIS_MODULE,
@@ -189,8 +205,7 @@ static struct cpuidle_driver omap4_idle_driver = {
/* C2 - CPU0 OFF + CPU1 OFF + MPU CSWR */
.exit_latency = 328 + 440,
.target_residency = 960,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED |
- CPUIDLE_FLAG_TIMER_STOP,
+ .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED,
.enter = omap_enter_idle_coupled,
.name = "C2",
.desc = "CPUx OFF, MPUSS CSWR",
@@ -199,8 +214,7 @@ static struct cpuidle_driver omap4_idle_driver = {
/* C3 - CPU0 OFF + CPU1 OFF + MPU OSWR */
.exit_latency = 460 + 518,
.target_residency = 1100,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED |
- CPUIDLE_FLAG_TIMER_STOP,
+ .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED,
.enter = omap_enter_idle_coupled,
.name = "C3",
.desc = "CPUx OFF, MPUSS OSWR",
@@ -231,5 +245,8 @@ int __init omap4_idle_init(void)
if (!cpu_clkdm[0] || !cpu_clkdm[1])
return -ENODEV;
+ /* Configure the broadcast timer on each cpu */
+ on_each_cpu(omap_setup_broadcast_timer, NULL, 1);
+
return cpuidle_register(&omap4_idle_driver, cpu_online_mask);
}
--
1.7.9.5
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