[PATCH 3.10 16/40] ARM: OMAP4: Fix the boot regression with CPU_IDLE enabled

Greg Kroah-Hartman
2014-06-09T22:48:47Z

From: Santosh Shilimkar <santosh.shilimkar@ti.com>

commit 4b353a706a86598ba47307c47301c3c428b79e09 upstream.

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.

Fixes: cb7094e8 (cpuidle / omap4 : use CPUIDLE_FLAG_TIMER_STOP flag)
Fixes: ff999b8a (cpuidle: OMAP4: remove timer broadcast initialization)
Cc: Roger Quadros <rogerq@ti.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Reported-tested-by: Roger Quadros <rogerq@ti.com>
Reported-tested-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm/mach-omap2/cpuidle44xx.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)

--- 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>
@@ -80,6 +81,7 @@ static int omap_enter_idle_coupled(struc
int index)
{
struct idle_statedata *cx = state_ptr + index;
+ int cpu_id = smp_processor_id();

/*
* CPU0 has to wait and stay ON until CPU1 is OFF state.
@@ -104,6 +106,8 @@ static int omap_enter_idle_coupled(struc
}
}

+ 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.
@@ -147,6 +151,8 @@ static int omap_enter_idle_coupled(struc
(cx->mpu_logic_state == PWRDM_POWER_OFF))
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;
@@ -154,6 +160,16 @@ 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,
@@ -171,8 +187,7 @@ static struct cpuidle_driver omap4_idle_
/* 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",
@@ -181,8 +196,7 @@ static struct cpuidle_driver omap4_idle_
/* 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",
@@ -213,5 +227,8 @@ 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);
}