Re: [PATCH] ALSA: hda: intel: Fix Optimus when GPU has no sound

[Maxim Mikityanskiy <maxtram95@gmail.com>]

On Sat, 07 Sep 2024 at 17:49:11 +0200, Takashi Iwai wrote:
> On Sat, 07 Sep 2024 15:45:41 +0200,
> Maxim Mikityanskiy wrote:
> > 
> > On Sat, 07 Sep 2024 at 12:06:25 +0200, Takashi Iwai wrote:
> > > On Fri, 06 Sep 2024 20:05:06 +0200,
> > > Maxim Mikityanskiy wrote:
> > > > 
> > > > On Thu, 05 Sep 2024 at 16:24:26 +0200, Takashi Iwai wrote:
> > > > > On Wed, 04 Sep 2024 22:39:55 +0200,
> > > > > Maxim Mikityanskiy wrote:
> > > > > > 
> > > > > > Lenovo IdeaPad Z570 with NVIDIA GeForce Ge 520M doesn't have sound on
> > > > 
> > > > Spotted a typo: s/520M/540M/
> > > > 
> > > > > > the discrete GPU. snd_hda_intel probes the device and schedules
> > > > > > azx_probe_continue(), which fails at azx_first_init(). The driver ends
> > > > > > up probed, but calls azx_free() and stops the chip. However, from the
> > > > > > runtime PM point of view, the device remains active, because the PCI
> > > > > > subsystem makes it active on probe, and it's still bound. It prevents
> > > > > > vga_switcheroo from turning off the DGPU (pci_create_device_link() syncs
> > > > > > power management for the video and audio devices).
> > > > > > 
> > > > > > Fix it by forcing the device to the suspended state in azx_free().
> > > > > > 
> > > > > > Fixes: 07f4f97d7b4b ("vga_switcheroo: Use device link for HDA controller")
> > > > > > Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com>
> > > > > 
> > > > > What if this device probe is skipped (e.g. adding your device entry to
> > > > > driver_denylist[] in hda_intel.c)?  Is the device also in the
> > > > > runtime-suspended state?
> > > > 
> > > > I added the following:
> > > > 
> > > > { PCI_DEVICE_SUB(0x10de, 0x0bea, 0x0000, 0x0000) },
> > > > 
> > > > The probe was apparently skipped (the device is not attached to a
> > > > driver), runtime_status=suspended, runtime_usage=0, the GPU goes to
> > > > DynOff.
> > > 
> > > OK, that's good.
> > > 
> > > > However, I'm not sure whether it's a good idea to blacklist 540M
> > > > entirely, as there might be other laptops with this GPU that have sound,
> > > > and AFAIK there are variants of Lenovo Z570 with other NVIDIA GPUs.
> > > 
> > > You should specify the PCI SSID of your device instead of 0:0 in the
> > > above, so that it's picked up only for yours.
> > 
> > Where can I get it?
> > 
> > # cat /sys/bus/pci/devices/0000\:01\:00.1/subsystem_vendor
> > 0x0000
> > # cat /sys/bus/pci/devices/0000\:01\:00.1/subsystem_device
> > 0x0000
> 
> Ouch, Lenovo didn't set it right.
> Alternatively we may introduce a deny list based on DMI.  Hmm...

A DMI-based quirk sounds better than blocking any NVIDIA 540M, it would
also allow handling alternative GPUs on this laptop model.

But could you explain what's wrong with a generic approach that I
suggest (probe_continue failed => mark as suspended)? It doesn't require
any lists. Any drawbacks?

> 
> 
> Takashi
> 
> 
> > 
> > Is it not the right place?
> > 
> > > 
> > > Takashi
> > > 
> > > > Another way to make vga_switcheroo work is to disable quirk_nvidia_hda,
> > > > although I don't know whether it can be done without recompiling the
> > > > kernel. In this case, 0000:01:00.1 doesn't even appear on the bus.
> > > > 
> > > > (Note that I need to set nouveau.modeset=2 either way, otherwise it
> > > > stays in DynPwr if the screen is on.)
> > > > 
> > > > > 
> > > > > 
> > > > > thanks,
> > > > > 
> > > > > Takashi
> > > > > 
> > > > > > ---
> > > > > >  sound/pci/hda/hda_intel.c | 14 +++++++++++++-
> > > > > >  1 file changed, 13 insertions(+), 1 deletion(-)
> > > > > > 
> > > > > > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> > > > > > index b79020adce63..65fcb92e11c7 100644
> > > > > > --- a/sound/pci/hda/hda_intel.c
> > > > > > +++ b/sound/pci/hda/hda_intel.c
> > > > > > @@ -1361,8 +1361,20 @@ static void azx_free(struct azx *chip)
> > > > > >  	if (use_vga_switcheroo(hda)) {
> > > > > >  		if (chip->disabled && hda->probe_continued)
> > > > > >  			snd_hda_unlock_devices(&chip->bus);
> > > > > > -		if (hda->vga_switcheroo_registered)
> > > > > > +		if (hda->vga_switcheroo_registered) {
> > > > > >  			vga_switcheroo_unregister_client(chip->pci);
> > > > > > +
> > > > > > +			/* Some GPUs don't have sound, and azx_first_init fails,
> > > > > > +			 * leaving the device probed but non-functional. As long
> > > > > > +			 * as it's probed, the PCI subsystem keeps its runtime
> > > > > > +			 * PM status as active. Force it to suspended (as we
> > > > > > +			 * actually stop the chip) to allow GPU to suspend via
> > > > > > +			 * vga_switcheroo.
> > > > > > +			 */
> > > > > > +			pm_runtime_disable(&pci->dev);
> > > > > > +			pm_runtime_set_suspended(&pci->dev);
> > > > > > +			pm_runtime_enable(&pci->dev);
> > > > > > +		}
> > > > > >  	}
> > > > > >  
> > > > > >  	if (bus->chip_init) {
> > > > > > -- 
> > > > > > 2.46.0
> > > > > >