On Tue, Feb 13, 2018 at 10:55 AM, Lukas Wunner <lukas@xxxxxxxxx> wrote: > On Tue, Feb 13, 2018 at 10:18:01AM +0100, Rafael J. Wysocki wrote: >> On Tue, Feb 13, 2018 at 12:14 AM, <Mario.Limonciello@xxxxxxxx> wrote: >> >> >> request before making any decisions here. >> >> > >> >> > It's a lack of proper D3hot support and GC6 support in Nouveau. >> >> >> >> Thanks, but that is still a bit enigmatic. >> >> >> >> What exactly do you mean by "proper D3hot support", in particular? >> >> >> > >> > I don't believe Nouveau or NVIDIA has support for D3hot at all from >> > what I've heard. I've not dug further into this. >> >> But Lukas is saying that Nouveau actually supports runtime PM, so I'm >> not sure what exactly the problem is with respect to this particular >> driver. > > Just providing some background info in the hope that it might be useful: > > nouveau runtime suspends to D3cold on Nvidia Optimus hybrid graphics > laptops, not on any other machines (e.g. desktop). The code is in > drivers/gpu/drm/nouveau/nouveau_acpi.c. It detects presence of Optimus > by looking for a specific _DSM. > > On older machines, power was cut using that _DSM. Newer machines instead > specify _PR3 resources for the root port above the GPU, so power is cut > once the GPU and the root port above it have runtime suspended. nouveau > detects and supports both mechanisms, as well as the ancient "HybridPower" > machines that preceded Optimus. Adding Peter Wu to cc, who is the most > knowledgable person I know for this. > > Mario mentions GC6, doing a bit of googling reveals this has to do with > power sequencing: > https://www.manualslib.com/manual/1273261/Clevo-N850hk1.html?page=67#manual > > It looks like a number of GPIO pins need to be toggled in just the right > order with just the right timing for the GPU to suspend and resume > properly. Now, normally this should all be handled by the firmware, > but apparently there's some OS cooperation necessary but people may > not be at liberty to talk about it or haven't been told everything > by Nvidia. > > AFAIK the proprietary Nvidia driver doesn't support Optimus at all. > That might be the real motivation for the patch. OK, that helps, thanks! It actually agrees with my last reply to Mika. -- 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
