On Sunday, April 01, 2012, Zhang Rui wrote: > On 日, 2012-04-01 at 09:47 +0200, Rafael J. Wysocki wrote: > > On Sunday, April 01, 2012, Aaron Lu wrote: > > > Hi, > > > > > > On Sun, Apr 01, 2012 at 03:03:39PM +0800, Zhang Rui wrote: > > > > First of all, I agree that we must evaluate _PS3 when setting device to > > > > either D3_HOT or D3_COLD. > > > Good. > > > > > > > > > > > And here is my understanding about D3/D3_HOT/D3_COLD, > > > > > > > > if _PR3 exists, it means the devices supports both D3_HOT and D3_COLD. > > > Agree. > > > > > > > > > > > if only _PS3 exists, we can only say that the state after evaluating > > > > _PS3 is D3, it could either be D3_HOT or D3_COLD, and this is device > > > > specific, which in your case, is D3_COLD. > > > I prefer Rafeal's definition, let's just *assume* the device is at D3 > > > cold after its _PS3 is executed. Unless it has _PR3, in which case, we > > > have a chance to put the device into D3 hot instead. > > > > > > > > > > > BTW, here is the description of _S0W in ACPI spec, > > > > If OSPM has not indicated that it supports _PR3 through the OSPM > > > > Platform-Wide Capabilities (see Section 6.2.10.2), then the value "3" > > > > corresponds to D3. If it has indicated _PR3 support, the value "3" > > > > represents D3hot and the value "4" represents D3cold. > > > > > > > > So IMO, the _S0W should return 3 in AMD's implementation as it does not > > > > have _PR3. > > > OK, sounds like a firmware bug. > > > Thanks for identifying this. > > > > I don't think this is a bug. It actually may return either 3 or 4, because > > there is no difference between them if there's no _PR3 (i.e. the action to > > carry out by software would only be different if _PR3 were present). > > > I mean, surely that software should handle this case. Well, exactly. :-) > But this is still a violation of ACPI spec, as the device has only one > D3 state, instead of D3_HOT/D3_COLD,, thus _S0W should return 3 instead. If software is expected to handle that case anyway, I wouldn't really call it a violation. What really matters is what software is supposed to do. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
