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Subject[PATCH] PM: fix calculation mistake in roll-over cases
Date
From: venu byravarasu <vbyravarasu@nvidia.com>

In case of jiffies roll over, delta is made zero.
Hence fixing it, after taking roll over into consideration.

Signed-off-by: venu byravarasu <vbyravarasu@nvidia.com>
---
When jiffies roll over, calculation of time spent in the
current state (stored in variable 'delta') is incorrect.
Hence fixing it, after taking roll over into consideration.
drivers/base/power/runtime.c | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 1079e03..bd93fb0 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -30,12 +30,13 @@ static int rpm_suspend(struct device *dev, int rpmflags);
void update_pm_runtime_accounting(struct device *dev)
{
unsigned long now = jiffies;
- int delta;
+ unsigned long delta;
+ unsigned long max_num = ~0;

delta = now - dev->power.accounting_timestamp;

- if (delta < 0)
- delta = 0;
+ if (now < dev->power.accounting_timestamp)
+ delta = max_num - dev->power.accounting_timestamp + now;

dev->power.accounting_timestamp = now;

--
1.7.1.1


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