From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FAKE_REPLY_C,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A3D9C43331 for ; Tue, 24 Mar 2020 17:50:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 588E72074D for ; Tue, 24 Mar 2020 17:50:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585072258; bh=CCEABUBAN9MRCpgZksVbrjdDahiV/d+RR5NEsl42kLY=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=1h/tP5RC7pXLfeA2wsF5Pf5TWrEo9/lVkY2iF9smp/91Ri9KuU2kSzJdVDYRWm2zv Gkrnegg5+YQVQpNMPbxqu+DSdZg+shJwxocimOV69DzqS2DcR/kuDpBlUg4aWq1KDE Rz22RX/togzkyJILbtxpn7pl/1WH5/tt38NkHYgY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727417AbgCXRu5 (ORCPT ); Tue, 24 Mar 2020 13:50:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:35302 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727366AbgCXRu5 (ORCPT ); Tue, 24 Mar 2020 13:50:57 -0400 Received: from localhost (mobile-166-175-186-165.mycingular.net [166.175.186.165]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5B93C206F6; Tue, 24 Mar 2020 17:50:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585072256; bh=CCEABUBAN9MRCpgZksVbrjdDahiV/d+RR5NEsl42kLY=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=oTKbBiukjqGnd1ubSkTzU8ZLakbO+PNdBHpsd8jDmeekp1cwfiFnpXrA2nBak0QkQ 9mCR81onE5mAvc0ko9+NVjWOYqRzaqDEoNZa9+n+ap7j4FuFUn2oQ2X8zJ2+5Dxm4T vFbo7RkPWVrOqpmSMGot0Yf4DD1FBSBxWL6lhhsE= Date: Tue, 24 Mar 2020 12:50:54 -0500 From: Bjorn Helgaas To: Karol Herbst Cc: LKML , Lyude Paul , "Rafael J . Wysocki" , Mika Westerberg , Linux PCI , Linux PM , dri-devel , nouveau , Mika Westerberg Subject: Re: [PATCH v7] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges Message-ID: <20200324175054.GA23029@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Mar 24, 2020 at 06:31:08PM +0100, Karol Herbst wrote: > On Sat, Mar 21, 2020 at 2:02 AM Karol Herbst wrote: > > > > On Fri, Mar 20, 2020 at 11:19 PM Bjorn Helgaas wrote: > > > > > > On Tue, Mar 10, 2020 at 08:26:27PM +0100, Karol Herbst wrote: > > > > Fixes the infamous 'runtime PM' bug many users are facing on Laptops with > > > > Nvidia Pascal GPUs by skipping said PCI power state changes on the GPU. > > > > > > > > Depending on the used kernel there might be messages like those in demsg: > > > > > > > > "nouveau 0000:01:00.0: Refused to change power state, currently in D3" > > > > "nouveau 0000:01:00.0: can't change power state from D3cold to D0 (config > > > > space inaccessible)" > > > > followed by backtraces of kernel crashes or timeouts within nouveau. > > > > > > > > It's still unkown why this issue exists, but this is a reliable workaround > > > > and solves a very annoying issue for user having to choose between a > > > > crashing kernel or higher power consumption of their Laptops. > > > > > > Thanks for the bugzilla link. The bugzilla mentions lots of mailing > > > list discussion. Can you include links to some of that? > > > > > > IIUC this basically just turns off PCI power management for the GPU. > > > Can you do that with something like the following? I don't know > > > anything about DRM, so I don't know where you could save the pm_cap, > > > but I'm sure the driver could keep it somewhere. > > > > > > > Sure this would work? From a quick look over the pci code, it looks > > like a of code would be skipped we really need, like the platform code > > to turn off the GPU via ACPI. But I could also remember incorrectly on > > how all of that worked again. I can of course try and see what the > > effect of this patch would be. And would the parent bus even go into > > D3hot if it knows one of its children is still at D0? Because that's > > what the result of that would be as well, no? And I know that if the > > bus stays in D0, that it has a negative impact on power consumption. > > > > Anyway, I will try that out, I am just not seeing how that would help. > > so it seems like that has worked unless I screwed up locally. Will do > some proper testing and then I think we won't need to go through the > pci tree anymore as no changes are required there with that. Hehe, looks like our responses crossed in the mail :) I hope further testing is still positive; let me know if not. Bjorn