From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Subject: Re: PCI: Revert "PCI: Add runtime PM support for PCIe ports" To: Lukas Wunner , David Airlie References: <20161228161816.GA19653@bhelgaas-glaptop.roam.corp.google.com> <20170104081639.GA21076@wunner.de> <20170104210954.GA11946@al> <59349185.1aqio7kYFn@aspire.rjw.lan> <1456065516.8360056.1483572074197.JavaMail.zimbra@redhat.com> <20170105150646.GB21446@wunner.de> Cc: "Rafael J. Wysocki" , Peter Wu , Bjorn Helgaas , Mika Westerberg , Kilian Singer , linux-pci , Alex Deucher , Peter Jones From: Hans de Goede Message-ID: <2562d75e-a770-3b9d-da3b-57c12896cd11@redhat.com> Date: Sat, 7 Jan 2017 12:45:35 +0100 MIME-Version: 1.0 In-Reply-To: <20170105150646.GB21446@wunner.de> Content-Type: text/plain; charset=windows-1252; format=flowed List-ID: Hi, On 05-01-17 16:06, Lukas Wunner wrote: > On Wed, Jan 04, 2017 at 06:21:14PM -0500, David Airlie wrote: >>> On Wednesday, January 04, 2017 10:09:54 PM Peter Wu wrote: >>>> On Wed, Jan 04, 2017 at 09:16:39AM +0100, Lukas Wunner wrote: >>>>> On Tue, Jan 03, 2017 at 06:05:57PM -0600, Bjorn Helgaas wrote: >>>>>> I don't *want* to apply the revert. It's on my for-linus branch as a >>>>>> worst-case scenario change if we can't figure out a better fix. >>>>>> >>>>>> The patch below is preferable, but I'd rather not take even it, >>>>>> because it takes away functionality and forces people to use a boot >>>>>> parameter to restore it. I expect that somebody will figure out how >>>>>> to fix the regression Kilian found and also keep the new functionality >>>>>> (without requiring boot parameters) before v4.10. >>>>> >>>>> The issue is constrained to hybrid graphics laptops with Nvidia discrete >>>>> GPU using nouveau. Hence it needs to be fixed in nouveau, not in the >>>>> PCI core. >>>> >>>> The problem is not necessarily in the nouveau driver, the same problem >>>> occurs when you enable RPM without loading nouveau. The issue is limited >>>> though to some newer hybrid graphics laptops with Nvidia GPUs. While a >>>> quirk can be added to nouveau, I think that a (temporary) quirk in core >>>> would also be reasonable (since it also occurs without nouveau). >>>> >>>>> (AFAIUI, laptops with AMD discrete GPU are not affected as it is known >>>>> when and how to call an ACPI method versus using PR3.) >>>>> >>>>> (Neither are laptops using the Nvidia proprietary driver as it doesn't >>>>> runtime suspend the card. But battery life will be terrible then.) >>>>> >>>>> We're at rc2 so the time frame for coming up with a fix is probably >>>>> 4 weeks. Peter and others have tried for months to reverse-engineer >>>>> how to handle runtime PM on newer Nvidia cards. It seems likely that >>>>> we'll not find the ultimate solution to the problem within 4 weeks. >>>> >>>> Yep, a quick proper fix seems unlikely. >>>> [ Help/ideas are welcome, I suspect that these failures to restore power >>>> on laptops designed for Win8+ all have the same cause, related to some >>>> unknown interaction between ACPI and PCI. Some links: >>>> https://bugzilla.kernel.org/show_bug.cgi?id=190861 >>>> https://bugzilla.kernel.org/show_bug.cgi?id=156341 ] >>>> >>>>> The way it is now, i.e. defaulting to PR3 when available, regresses >>>>> certain laptops such as Kilian's. If on the other hand we default to >>>>> DSM when available, we'll regress certain other laptops, as Peter has >>>>> pointed out. Whitelisting or blacklisting laptops doesn't seem a good >>>>> approach either, ideally we'd want to use PR3 as Windows does. >>>>> >>>>> As said, the only short-term solution I see is to add an "optimus" >>>>> module_param to nouveau to allow users to select which method to use. >>>>> So in Kilian's case an additional command line parameter would be >>>>> necessary to fix the issue. >>>>> >>>>> Does anyone see a better solution or can we agree on this one? If so >>>>> I can come up with a patch. This could go in via Dave Airlie's tree. >>>> >>>> As pcie_port_pm=off already reverts to DSM, I do not think that an >>>> additional (temporary) nouveau module parameter is going to help. I >>>> instead propose a (hopefully temporary) quirk in pci core that disables >>>> D3cold RPM for just Kilians Lenovo laptop (basically defaulting to >>>> pcie_port_pm=off). Then the option pcie_port_pm=force can still be used >>>> to test possible solutions in the future. >>> >>> I would rather add a quirk to the ACPI core to prevent the power resources in >>> question from being enumerated. Or even to prevent ACPI PM from being >>> used for the port in question. >> >> I do have a W541 in a cupboard in the office somewhere, but I won't be close to >> it for a couple of weeks. The W541 was the first place I tested the pm patches >> so I'm kinda wondering whether it's all W541's or just some specific model/bios >> combo. >> >> However I'm pretty much unavailable to do anything much until late Jan on this. > > Is there anyone else at Red Hat who might be able to look into this? > > ISTR that Hans de Goede is working on improving laptop support in Fedora, > and Peter Jones recently got a patch merged for the W541 with the exact > same firmware Kilian is using to work around a botched EFI memory map. > Adding them to cc: in the hope that they may be able to help. > > @Peter, have you noticed issues with the discrete Nvidia GPU on your W541 > related to runtime suspend and system sleep? I've a W541 sitting in my home office at well. I will take it through some gpu runtime suspend/resume testing. Which kernel introduces the problem I'm looking for ? I believe mine has the old BIOS / EFI which is less troublesome so I will first see if I can reproduce the problem with that and then upgrade to see if that introduces the problem. Peter IIRC you said that after upgrading the firmware I need a new enough kernel to be able to even boot, from which kernel onwards will the machine boot with the new firmware ? Also is it possible to downgrade the EFI again ? ... Regards, Hans