Re: [PATCH 4/4] ALSA: hda - Wake the codec up on pin/ELD notify events

[David Henningsson <david.henningsson@canonical.com>]

On 2015-11-26 16:23, Takashi Iwai wrote:
> On Thu, 26 Nov 2015 16:08:06 +0100,
> David Henningsson wrote:
>>
>>
>>
>> On 2015-11-26 10:24, Takashi Iwai wrote:
>>> On Thu, 26 Nov 2015 10:16:17 +0100,
>>> Zhang, Xiong Y wrote:
>>>>
>>>>
>>>>> On Thu, 26 Nov 2015 08:57:30 +0100,
>>>>> Zhang, Xiong Y wrote:
>>>>>>
>>>>>>>>> BTW, I have a patchset to avoid the audio h/w wakeup by a new
>>>>>>>>> component ops to get ELD and connection states.  It was posted to
>>>>>>>>> alsa-devel shortly ago just as a reference, but this should work well
>>>>>>>>> in such a case, too.  The test patches are found in test/hdmi-jack
>>>>>>>>> branch of my sound git tree.
>>>>>>>
>>>>>>> Did you try this branch (merge onto intel-test-nightly)?
>>>>>>>
>>>>>> [Zhang, Xiong Y] Yes, this branch could fix my issue.
>>>>>
>>>>> OK, good to hear.  But this isn't for 4.4 or backport, as it's more
>>>>> radical changes.
>>>>>
>>>>> Could you check the patch below instead?  This suppresses the notifier
>>>>> handling during suspend.  It's bad, but the hotplug should be still
>>>>> handled via normal unsol event, so it should keep working, good enough
>>>>> as a stop gap.
>>>>>
>>>>>
>>>>> Takashi
>>>>>
>>>>> ---
>>>>> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
>>>>> index bdb6f226d006..f7c70e2ae65c 100644
>>>>> --- a/sound/pci/hda/patch_hdmi.c
>>>>> +++ b/sound/pci/hda/patch_hdmi.c
>>>>> @@ -33,6 +33,7 @@
>>>>>    #include <linux/delay.h>
>>>>>    #include <linux/slab.h>
>>>>>    #include <linux/module.h>
>>>>> +#include <linux/pm_runtime.h>
>>>>>    #include <sound/core.h>
>>>>>    #include <sound/jack.h>
>>>>>    #include <sound/asoundef.h>
>>>>> @@ -2352,7 +2353,9 @@ static void intel_pin_eld_notify(void *audio_ptr, int
>>>>> port)
>>>>>    	struct hda_codec *codec = audio_ptr;
>>>>>    	int pin_nid = port + 0x04;
>>>>>
>>>>> -	check_presence_and_report(codec, pin_nid);
>>>>> +	if (!atomic_read(&codec->core.in_pm) &&
>>>>> +	    !pm_runtime_suspended(hda_codec_dev(codec)))
>>>>> +		check_presence_and_report(codec, pin_nid);
>>>>>    }
>>>>>
>>>>>    static int patch_generic_hdmi(struct hda_codec *codec)
>>>> [Zhang, Xiong Y]  this patch couldn't remove the error message. So audio controller isn't in Runtime D3 after azx_suspend().
>>>
>>> OK, then the problem isn't about the HD-audio driver but rather i915
>>> driver.  As already mentioned, i915 driver shouldn't issue eld_notify
>>> callback in the suspend code path.
>>
>> We don't have a complete drm log so I'm only speculating here; but the
>> HDA log seems to indicate the power well is off when we try to talk to
>> the HDA controller. That means either the i915 shut it down while we
>> were holding a lock on it, or HDA tried to lock it and that didn't make
>> it through; in which case the HDA side should handle an error from
>> get_power more gracefully...?
>
> My understanding is that it's triggered *during* i915 suspend.  Then
> the path calls the HDA callback, and HDA controller tries to get power
> and proceeds as it has no idea that it's being shut off.

Well; that can also be stopped by letting the get_power call return a 
failure code in case i915 is trying to suspend itself. That seems more 
robust to me, as it could potentially avoid other S3 races too...?

>
> Unfortunately, neither get_power callback or the corresponding HDA
> code has a capability to check that state.  So, changing / fixing this
> there would be nice but very hard.

Surely the i915 driver has some "am_i_suspending" variable it can check 
in the get_power callback?

>
> So I believe it's easier to avoid calling the eld_notify callback from
> i915 side during its suspend code.
>
>
> Takashi
>

-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic
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