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

[Hui Wang]

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.

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
>>