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@xxxxxxxxxxxxx>
> > 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.
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
> >>
>
