From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754258Ab2LCLR3 (ORCPT ); Mon, 3 Dec 2012 06:17:29 -0500 Received: from cantor2.suse.de ([195.135.220.15]:52477 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754104Ab2LCLRT (ORCPT ); Mon, 3 Dec 2012 06:17:19 -0500 Date: Mon, 03 Dec 2012 12:17:17 +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 09:45:39 +0100, Takashi Iwai wrote: > > 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? Ping. If this really works, I'd like to queue it for 3.8 merge, at least... thanks, Takashi > > > 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: