cpuidle: use last_state which can reflect the actual state entered

cpuidle accounts the idle time for the C-state it was trying to enter and
not to the actual state that the driver eventually entered. The driver may
select a different state than the one chosen by cpuidle due to
constraints like bus-mastering, etc.

Change the time acounting code to look at the dev->last_state after
returning from target_state->enter(). Driver can modify dev->last_state
internally, inside the enter routine to reflect the actual C-state
entered.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Tested-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 5ce07b517c58..eb2cade562db 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -67,8 +67,11 @@ static void cpuidle_idle_call(void)
         target_state = &dev->states[next_state];
 
         /* enter the state and update stats */
-        dev->last_residency = target_state->enter(dev, target_state);
         dev->last_state = target_state;
+        dev->last_residency = target_state->enter(dev, target_state);
+        if (dev->last_state)
+                target_state = dev->last_state;
+
         target_state->time += (unsigned long long)dev->last_residency;
         target_state->usage++;