[08/13] cpufreq: omap: call CPUFREQ_POSTCHANGE notfier in error cases

Message ID 957838f1065ccc20b0252e0a6d37b61f6b173970.1371630975.git.viresh.kumar@linaro.org
State Accepted
Headers show

Commit Message

Viresh Kumar June 19, 2013, 8:53 a.m.
PRECHANGE and POSTCHANGE notifiers must be called in groups, i.e either both
should be called or both shouldn't be.

In case we have started PRECHANGE notifier and found an error, we must call
POSTCHANGE notifier with freqs.new = freqs.old to guarantee that sequence of
calling notifiers is complete.

Omap driver was taking care of it well, but wasn't restoring freqs.new to
freqs.old in some cases. I wasn't required to add code for it as moving
PRECHANGE notifier down was a better option, so that we call it just before
starting frequency transition.

Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/omap-cpufreq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Santosh Shilimkar June 19, 2013, 2:44 p.m. | #1
On Wednesday 19 June 2013 04:53 AM, Viresh Kumar wrote:
> PRECHANGE and POSTCHANGE notifiers must be called in groups, i.e either both
> should be called or both shouldn't be.
> 
> In case we have started PRECHANGE notifier and found an error, we must call
> POSTCHANGE notifier with freqs.new = freqs.old to guarantee that sequence of
> calling notifiers is complete.
> 
> Omap driver was taking care of it well, but wasn't restoring freqs.new to
> freqs.old in some cases. I wasn't required to add code for it as moving
> PRECHANGE notifier down was a better option, so that we call it just before
> starting frequency transition.
> 
> Cca: Santosh Shilimkar <santosh.shilimkar@ti.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
Looks safe to me.
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

Patch

diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
index 0279d18..29468a5 100644
--- a/drivers/cpufreq/omap-cpufreq.c
+++ b/drivers/cpufreq/omap-cpufreq.c
@@ -93,9 +93,6 @@  static int omap_target(struct cpufreq_policy *policy,
 	if (freqs.old == freqs.new && policy->cur == freqs.new)
 		return ret;
 
-	/* notifiers */
-	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
-
 	freq = freqs.new * 1000;
 	ret = clk_round_rate(mpu_clk, freq);
 	if (IS_ERR_VALUE(ret)) {
@@ -125,6 +122,9 @@  static int omap_target(struct cpufreq_policy *policy,
 		freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
 		freqs.new / 1000, volt ? volt / 1000 : -1);
 
+	/* notifiers */
+	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
+
 	/* scaling up?  scale voltage before frequency */
 	if (mpu_reg && (freqs.new > freqs.old)) {
 		r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);