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Kevin Hilman authored
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 <khilman@ti.com> Signed-off-by:
Rafael J. Wysocki <rjw@sisk.pl>
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