From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751206AbeCIJa0 (ORCPT ); Fri, 9 Mar 2018 04:30:26 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:40109 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920AbeCIJaY (ORCPT ); Fri, 9 Mar 2018 04:30:24 -0500 X-Google-Smtp-Source: AG47ELtWty17yN90WBiy8DewWiWngNJj1jH5hXxISB8medR+j4Q4FJKjBya5NqQljHVjBumkON2n8A== Content-Type: text/plain; charset=utf-8; delsp=yes; format=flowed Mime-Version: 1.0 (Mac OS X Mail 11.3 \(3445.6.15\)) Subject: Re: [PATCH v2 3/3] ALSA: hda: Disabled unused audio controller for Dell platforms with Switchable Graphics From: Kai Heng Feng In-Reply-To: <20180309090223.xb55ltac4pfesdrh@pali> Date: Fri, 9 Mar 2018 17:30:15 +0800 Cc: mjg59@srcf.ucam.org, dvhart@infradead.org, andy@infradead.org, Mario Limonciello , tiwai@suse.com, platform-driver-x86@vger.kernel.org, Linux Kernel Mailing List , alsa-devel@alsa-project.org Content-Transfer-Encoding: 8bit Message-Id: <723DA929-C9FA-4F69-8D3A-03D8A75D09A6@canonical.com> References: <20180308091023.9061-1-kai.heng.feng@canonical.com> <20180308091023.9061-3-kai.heng.feng@canonical.com> <20180309090223.xb55ltac4pfesdrh@pali> To: =?utf-8?Q?Pali_Roh=C3=A1r?= X-Mailer: Apple Mail (2.3445.6.15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Mar 9, 2018, at 5:02 PM, Pali Rohár wrote: > > On Thursday 08 March 2018 17:10:23 Kai-Heng Feng wrote: >> Some Dell platforms (Preicsion 7510/7710/7520/7720) have a BIOS option >> "Switchable Graphics" (SG). >> >> When SG is enabled, we have: >> 00:02.0 VGA compatible controller: Intel Corporation Device 591b (rev 04) >> 00:1f.3 Audio device: Intel Corporation CM238 HD Audio Controller (rev 31) >> 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. >> [AMD/ATI] Ellesmere [Polaris10] >> 01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere >> [Radeon RX 580] >> >> The Intel Audio outputs all the sound, including HDMI audio. The audio >> controller comes with AMD graphics doesn't get used. >> >> When SG is disabled, we have: >> 00:1f.3 Audio device: Intel Corporation CM238 HD Audio Controller (rev 31) >> 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. >> [AMD/ATI] Ellesmere [Polaris10] >> 01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere >> [Radeon RX 580] >> >> Now it's a typical discrete-only system. HDMI audio comes from AMD audio >> controller, others from Intel audio controller. >> >> When SG is enabled, the unused AMD audio controller still exposes its >> sysfs, so userspace still opens the control file and stream. If >> userspace tries to output sound through the stream, it hangs when >> runtime suspend kicks in: >> [ 12.796265] snd_hda_intel 0000:01:00.1: Disabling via vga_switcheroo >> [ 12.796367] snd_hda_intel 0000:01:00.1: Cannot lock devices! >> >> Since the discrete audio controller isn't useful when SG enabled, we >> should just disable the device. >> >> Signed-off-by: Kai-Heng Feng >> --- >> v2: Mario suggested to squash the HDA part into the same series. >> >> sound/pci/hda/hda_intel.c | 35 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 35 insertions(+) >> >> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c >> index 96143df19b21..8e3e8b88624a 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 */ >> @@ -1620,6 +1621,35 @@ static void check_msi(struct azx *chip) >> } >> } >> >> +#if IS_ENABLED(CONFIG_DELL_LAPTOP) >> +static bool check_dell_switchable_gfx(struct pci_dev *pdev) >> +{ >> + static int (*dell_switchable_gfx_enabled_func)(bool *); >> + bool enabled; >> + int err; >> + >> + if (pdev->vendor != PCI_VENDOR_ID_ATI || >> + pdev->subsystem_vendor != PCI_VENDOR_ID_DELL) >> + return false; > > Are you sure that you want to do this check unconditionally on all > machines which have enabled CONFIG_DELL_LAPTOP? > > Subvendor ID_DELL for dell specific code is not suspicious, but ID_ATI > is. What would happen if ATI vendor changes to NVIDIA or other which is > not related to Dell? We only check it when it's both ATI and DELL, otherwise just return false? The platform does have a NVIDIA variant, but the discrete NVIDIA have a audio controller, hence it doesn't have the issue. The issue only happens to AMD/ATI configs with "Switchable Graphics" option. > > Interesting question would be, how handle this situation Windows? I don't know how this platform handles this on Windows, I guess we need Mario to shed some lights here. Kai-Heng > >> + dell_switchable_gfx_enabled_func = >> + symbol_request(dell_switchable_gfx_enabled); >> + if (!dell_switchable_gfx_enabled_func) >> + return false; >> + >> + err = dell_switchable_gfx_enabled_func(&enabled); >> + >> + symbol_put(dell_switchable_gfx_enabled); >> + >> + return !err ? enabled : false; >> +} >> +#else >> +static bool check_dell_switchable_gfx(struct pci_dev *pdev) >> +{ >> + return false; >> +} >> +#endif >> + >> /* check the snoop mode availability */ >> static void azx_check_snoop_available(struct azx *chip) >> { >> @@ -1702,6 +1732,11 @@ static int azx_create(struct snd_card *card, >> struct pci_dev *pci, >> if (err < 0) >> return err; >> >> + if (check_dell_switchable_gfx(pci)) { >> + pci_disable_device(pci); >> + return -ENODEV; >> + } >> + >> hda = kzalloc(sizeof(*hda), GFP_KERNEL); >> if (!hda) { >> pci_disable_device(pci); > > -- > Pali Rohár > pali.rohar@gmail.com