[PATCH] ALSA: hda: enable the runtime_pm for non-vgaswitcheroo hda controllers

[Takashi Iwai]

On Tue, 14 Apr 2020 14:40:35 +0200,
Takashi Iwai wrote:
> 
> On Tue, 14 Apr 2020 14:35:50 +0200,
> Hui Wang wrote:
> > 
> > 
> > On 2020/4/14 下午6:27, Takashi Iwai wrote:
> > > On Tue, 14 Apr 2020 12:14:05 +0200,
> > > Hui Wang wrote:
> > >> Before the pci_driver->probe() is called, the pci subsystem calls
> > >> runtime_forbib() and runtime_get_sync() on this pci dev, so only call
> > >> runtime_put_autosuspend() is not enough to enable the runtime_pm on
> > >> this device.
> > >>
> > >> For controllers with vgaswitcheroo feature, the pci/quirks.c will call
> > >> runtime_allow() for this dev, then the controllers could enter
> > >> rt_idle/suspend/resume, but for non-vgaswitcheroo controllers like
> > >> Intel hda controllers, the runtime_pm is not enabled even it calls
> > >> put_autosuspend(). Need to call runtime_allow() for those controllers
> > >> in the hda driver.
> > >>
> > >> Signed-off-by: Hui Wang <hui.wang at canonical.com>
> > > Was this behavior changed from the earlier kernels?  I thought this
> > > was left untouched because it's supposed to be set via udev rules or
> > > such.
> > 
> > Oh, I don't know that,  according to my test with ubuntu rootfs, the
> > runtime pm is not enabled on Intel's hda controllers. But with the sof
> > driver, the controller driver calls runtime_allow()
> > (soc/sof/sof-pci-dev.c), so I sent this patch.
> 
> OK, I just watned to know the situation.  So it's no regression but
> rather to align the behavior among drivers, and that's fine.
> Let's take the patch, then.

On the second thought, we can drop the vga_switcheroo check and always
allow it?  We do want to enable in anyway, and calling it twice should
be fine.


thanks,

Takashi


> 
> 
> thanks,
> 
> Takashi
> 
> > 
> > Regards,
> > 
> > Hui.
> > 
> > > OTOH, enabling the runtime PM is almost mandatory for modern systems,
> > > and I'm fine to apply this kind of forcible enablement.
> > >
> > >
> > > thanks,
> > >
> > > Takashi
> > >
> > >
> > >> ---
> > >>   sound/pci/hda/hda_intel.c | 2 ++
> > >>   1 file changed, 2 insertions(+)
> > >>
> > >> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> > >> index 8519051a426e..779705bef88b 100644
> > >> --- a/sound/pci/hda/hda_intel.c
> > >> +++ b/sound/pci/hda/hda_intel.c
> > >> @@ -2356,6 +2356,8 @@ static int azx_probe_continue(struct azx *chip)
> > >>     	if (azx_has_pm_runtime(chip)) {
> > >>   		pm_runtime_use_autosuspend(&pci->dev);
> > >> +		if (!use_vga_switcheroo(chip))
> > >> +			pm_runtime_allow(&pci->dev);
> > >>   		pm_runtime_put_autosuspend(&pci->dev);
> > >>   	}
> > >>   -- 
> > >> 2.17.1
> > >>
> >