Messages in this thread | | | Subject | Re: [PATCH v2 3/3] ALSA: hda: Disabled unused audio controller for Dell platforms with Switchable Graphics | From | Kai Heng Feng <> | Date | Fri, 9 Mar 2018 17:30:15 +0800 |
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> On Mar 9, 2018, at 5:02 PM, Pali Rohár <pali.rohar@gmail.com> 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 <kai.heng.feng@canonical.com> >> --- >> 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 <linux/clocksource.h> >> #include <linux/time.h> >> #include <linux/completion.h> >> +#include <linux/dell-common.h> >> >> #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
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