[PATCH 1/1] PM / Runtime: let rpm_resume fail if rpm disabled and device suspended.

Allen Yu
2014-06-14T09:58:45Z

dev->power.is_suspended is set after core suspends device during system suspend.
This flag mostly means device is not operational (all I/O been quiesced, no more
data read or write acceptible, etc.), hence it's dangerous to access hardware if
device is suspended even though runtime PM status is RPM_ACTIVE.

In turn, we should allow device to be accessed in case device is *not* suspended
and runtime PM status is RPM_ACTIVE, even if runtime PM disabled. This corner case
can happen to a device in a generic PM domain if the domain is not powered off while
preparing for a system-wide power transition. In this case, runtime PM status will
be set to RPM_ACTIVE and then runtime PM is disabled. After that, device driver may
call pm_runtime_get_sync() and rpm_resume() should return 1, because the device is
still active as long as not been suspended.

Signed-off-by: Allen Yu <alleny@nvidia.com>
---
drivers/base/power/runtime.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 67c7938..39885f1 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -608,7 +608,7 @@ static int rpm_resume(struct device *dev, int rpmflags)
repeat:
if (dev->power.runtime_error)
retval = -EINVAL;
- else if (dev->power.disable_depth == 1 && dev->power.is_suspended
+ else if (dev->power.disable_depth == 1 && !dev->power.is_suspended
&& dev->power.runtime_status == RPM_ACTIVE)
retval = 1;
else if (dev->power.disable_depth > 0)
--
1.8.1.5