From 6f3c77b040fc24708228607bba504878de5236d1 Mon Sep 17 00:00:00 2001 From: Kevin Hilman Date: Fri, 21 Sep 2012 22:47:34 +0000 Subject: PM / Runtime: let rpm_resume() succeed if RPM_ACTIVE, even when disabled, v2 There are several drivers where the return value of pm_runtime_get_sync() is used to decide whether or not it is safe to access hardware and that don't provide .suspend() callbacks for system suspend (but may use late/noirq callbacks.) If such a driver happens to call pm_runtime_get_sync() during system suspend, after the core has disabled runtime PM, it will get the error code and will decide that the hardware should not be accessed, although this may be a wrong conclusion, depending on the state of the device when runtime PM was disabled. Drivers might work around this problem by using a test like: ret = pm_runtime_get_sync(dev); if (!ret || (ret == -EACCES && driver_private_data(dev)->suspended)) { /* access hardware */ } where driver_private_data(dev)->suspended is a flag set by the driver's .suspend() method (that would have to be added for this purpose). However, that potentially would need to be done by multiple drivers which means quite a lot of duplicated code and bloat. To avoid that we can use the observation that the core sets dev->power.is_suspended before disabling runtime PM and use that instead of the driver's private flag. Still, potentially many drivers would need to repeat that same check in quite a few places, so it's better to let the core do it. Then we can be a bit smarter and check whether or not runtime PM was disabled by the core only (disable_depth == 1) or by someone else in addition to the core (disable_depth > 1). In the former case rpm_resume() can return 1 if the runtime PM status is RPM_ACTIVE, because it means the device was active when the core disabled runtime PM. In the latter case it should still return -EACCES, because it isn't clear why runtime PM has been disabled. Tested on AM3730/Beagle-xM where a wakeup IRQ firing during the late suspend phase triggers runtime PM activity in the I2C driver since the wakeup IRQ is on an I2C-connected PMIC. [rjw: Modified whitespace to follow the file's convention.] Signed-off-by: Kevin Hilman Signed-off-by: Rafael J. Wysocki --- drivers/base/power/runtime.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/base') diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 7d9c1cb1c39a..3148b10dc2e5 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -509,6 +509,9 @@ 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 + && dev->power.runtime_status == RPM_ACTIVE) + retval = 1; else if (dev->power.disable_depth > 0) retval = -EACCES; if (retval) -- cgit v1.2.3