From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753406Ab2K1Ipm (ORCPT ); Wed, 28 Nov 2012 03:45:42 -0500 Received: from cantor2.suse.de ([195.135.220.15]:58798 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753158Ab2K1Ipl (ORCPT ); Wed, 28 Nov 2012 03:45:41 -0500 Date: Wed, 28 Nov 2012 09:45:39 +0100 Message-ID: From: Takashi Iwai To: Daniel J Blueman Cc: Seth Forshee , Dave Airlie , Linux Kernel Subject: Re: switcheroo registration vs switching race... In-Reply-To: References: User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.2 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org At Wed, 28 Nov 2012 11:45:07 +0800, Daniel J Blueman wrote: > > Hi Seth, Dave, Takashi, > > If I power down the unused discrete GPU before lightdm starts by > fiddling with the sysfs file [1] in the upstart script, I see a race > manifesting as the discrete GPU's HDA controller timing out to > commands [2]. > > Adding some debug, I see that the registered audio devices are put > into D3 before the GPU is, but it turns out that the discrete (and > internal) GPU's HDA controller gets registered a bit later, so the > list is empty. The symptom is since the HDA driver it's talking to > hardware which is now in D3. > > We could add a mutex to nouveau to allow us to wait for the DGPU HDA > controller, but perhaps this should be solved at a higher level in the > vgaswitcheroo code; what do you think? Maybe it's a side effect for the recent effort to fix another race in the probe. A part of them problem is that the registration is done at the very last of probing. Instead of delaying the registration, how about the patch below? Takashi --- diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index 4bb52da..17fbd68 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -49,6 +49,7 @@ #include #include #include +#include #ifdef CONFIG_X86 /* for snoop control */ @@ -469,6 +470,7 @@ struct azx { /* locks */ spinlock_t reg_lock; struct mutex open_mutex; + struct completion probe_wait; /* streams (x num_streams) */ struct azx_dev *azx_dev; @@ -2790,6 +2792,7 @@ static bool azx_vs_can_switch(struct pci_dev *pci) struct snd_card *card = pci_get_drvdata(pci); struct azx *chip = card->private_data; + wait_for_completion(&chip->probe_wait); if (chip->init_failed) return false; if (chip->disabled || !chip->bus) @@ -2851,6 +2854,9 @@ static int azx_free(struct azx *chip) azx_notifier_unregister(chip); + chip->init_failed = 1; /* to be sure */ + complete(&chip->probe_wait); + if (use_vga_switcheroo(chip)) { if (chip->disabled && chip->bus) snd_hda_unlock_devices(chip->bus); @@ -3156,6 +3162,7 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci, INIT_LIST_HEAD(&chip->pcm_list); INIT_LIST_HEAD(&chip->list); init_vga_switcheroo(chip); + init_completion(&chip->probe_wait); chip->position_fix[0] = chip->position_fix[1] = check_position_fix(chip, position_fix[dev]); @@ -3462,6 +3469,13 @@ static int __devinit azx_probe(struct pci_dev *pci, } #endif /* CONFIG_SND_HDA_PATCH_LOADER */ + err = register_vga_switcheroo(chip); + if (err < 0) { + snd_printk(KERN_ERR SFX + "Error registering VGA-switcheroo client\n"); + goto out_free; + } + if (probe_now) { err = azx_probe_continue(chip); if (err < 0) @@ -3473,14 +3487,8 @@ static int __devinit azx_probe(struct pci_dev *pci, if (pci_dev_run_wake(pci)) pm_runtime_put_noidle(&pci->dev); - err = register_vga_switcheroo(chip); - if (err < 0) { - snd_printk(KERN_ERR SFX - "Error registering VGA-switcheroo client\n"); - goto out_free; - } - dev++; + complete(&chip->probe_wait); return 0; out_free: