Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752605Ab2JILYA (ORCPT ); Tue, 9 Oct 2012 07:24:00 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:33471 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751278Ab2JILX5 (ORCPT ); Tue, 9 Oct 2012 07:23:57 -0400 MIME-Version: 1.0 X-Originating-IP: [116.14.92.167] In-Reply-To: References: Date: Tue, 9 Oct 2012 19:23:56 +0800 Message-ID: Subject: Re: [3.6-rc7] switcheroo race with Intel HDA... From: Daniel J Blueman To: Takashi Iwai Cc: Dave Airlie , Linux Kernel , alsa-devel@alsa-project.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2266 Lines: 56 On 9 October 2012 18:07, Takashi Iwai wrote: > At Tue, 09 Oct 2012 12:04:08 +0200, > Takashi Iwai wrote: >> >> At Tue, 9 Oct 2012 00:34:09 +0800, >> Daniel J Blueman wrote: >> > >> > On 8 October 2012 20:58, Takashi Iwai wrote: >> > > At Tue, 25 Sep 2012 13:20:05 +0800, >> > > Daniel J Blueman wrote: >> > >> On my Macbook with a discrete Nvidia GPU, there is a race between >> > >> selecting the integrated GPU and putting the discrete GPU into D3 [1], >> > >> reliably causing a kernel oops [2]. >> > >> >> > >> Introducing a delay of ~1s between the calls prevents this. When the >> > >> second 'OFF' write path executes, it looks like struct azx at >> > >> card->private_data hasn't yet been allocated yet [3], so there is >> > >> likely some locking missing. >> > > >> > > It's rather pci_get_drvdata() returning NULL (i.e. card is NULL, thus >> > > card->private_data causes Oops). Could you check the patch like below >> > > and see whether you get a kernel warning (but no Oops) or the problem >> > > gets fixed by shifting the assignment of pci drvdata? >> > [...] >> > >> > Good patching. Calling pci_set_drvdata later prevents the oops in HDA, >> > though we see unexpected 0x0 responses in the response ring buffer >> > [1], which we don't see when there's a >~1.5s delay between IGD and >> > OFF. >> >> If the previous patch fixed, it means that the switching occurred >> during the device was being probed. Maybe a better approach to >> register the VGA switcheroo after the proper initialization. >> >> The patch below is a revised one. Please give it a try. > > Also, it's not clear which card spews the spurious response. > Apply the patch below in addition. [...] hda-intel: 0000:01:00.1: spurious response 0x0:0x0, last cmd=0x1f0004 $ lspci -s :1:0.1 01:00.1 Audio device: NVIDIA Corporation Device 0e1b (rev ff) It's the NVIDIA device which presumably hasn't completed it's transition to D3 at the time the OFF is executed. Thanks, Daniel -- Daniel J Blueman -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/