On Tuesday, July 30, 2013 07:43:48 AM Aaron Lu wrote: > On 07/30/2013 06:21 AM, Rafael J. Wysocki wrote: > > On Monday, July 29, 2013 10:09:53 PM Aaron Lu wrote: > >> On 07/27/2013 09:10 PM, Rafael J. Wysocki wrote: > >>> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > >>> > >>> Make acpi_device_set_power() check if the given device is power > >>> manageable before checking if the given power state is valid for that > >>> device. Otherwise it will print that "Device does not support" that > >>> power state into the kernel log, which may not make sense for some > >>> power states (D0 and D3cold are supported by all devices by > >>> definition). > >> > >> It will not print "Device does not support" that power state if that > >> power state is D0 or D3cold since we have unconditionally set those two > >> power state's valid flag. > > > > So you didn't actually looked at acpi_bus_get_power_flags() that set the > > power.states[].flags.valid flag, because If you had looked at it, you would > > have seen that that's not the case. > > > > No, we don't set the valid flag for devices that aren't power manageable > > (i.e. have flags.power_manageable unset), which is the *whole* *point* of > > this change. > > Right, I missed this. Sorry for the noise. > > > > >> OTOH, what value should we return for a device node that is not power > >> manageable in acpi_device_set_power when the target state is D0 or D3 > >> cold? The old behavior is to return 0, meanning success without taking > >> any actual action. > >> > >> In acpi_bus_set_power, if the device is not power manageable, we will > >> return -ENODEV; in acpi_dev_pm_full/low_power, we will return 0 as in > >> the original acpi_device_set_power. So return -EINVAL here is correct? > > > > No, the original acpi_device_set_power() will return -ENODEV then, but > > in my opinion returning -EINVAL is more accurate, because "power > > manageable" means "you can change power state of it". > > Shall I prepare a patch to update the errno in acpi_bus_set_power? In fact, it doesn't need to check flags.power_manageable after this patch and the debug message won't be missed I think, so please just remove the whole if () from there, if that's not a problem. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
