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Subject[PATCH] PM/runtime: Optimize pm_runtime_autosuspend_expiration()
pm_runtime_autosuspend_expiration calls ktime_get_mono_fast_ns
even when its returned value may be unused. Therefore get
current time later and remove gotos while there.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
---
This patch is based on top of bleeding-edge branch, where
"[PATCH v2 ] PM-runtime: fix deadlock with ktime" is sitting.
I expect v3 of that patch, which should not harm this one.
It is meant to replace "PM/runtime: Do not needlessly call ktime_get"
sent earlier.

drivers/base/power/runtime.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 65e2b5f48e0c..7bbe28faca8d 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -145,24 +145,21 @@ static void pm_runtime_cancel_pending(struct device *dev)
u64 pm_runtime_autosuspend_expiration(struct device *dev)
{
int autosuspend_delay;
- u64 last_busy, expires = 0;
- u64 now = ktime_get_mono_fast_ns();
+ u64 expires;

if (!dev->power.use_autosuspend)
- goto out;
+ return 0;

autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
if (autosuspend_delay < 0)
- goto out;
-
- last_busy = READ_ONCE(dev->power.last_busy);
+ return 0;

- expires = last_busy + (u64)autosuspend_delay * NSEC_PER_MSEC;
- if (expires <= now)
- expires = 0; /* Already expired. */
+ expires = READ_ONCE(dev->power.last_busy);
+ expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
+ if (expires > ktime_get_mono_fast_ns())
+ return expires; /* Expires in the future */

- out:
- return expires;
+ return 0;
}
EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);

--
2.20.1
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