linux-kernel - Re: [PATCH] ALSA: hda: Skip creating captures in SOF context

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Message-ID: <514f0fda-9475-e163-fd64-0bc675dd3447@linux.intel.com>
Date:   Wed, 20 Jul 2022 08:31:18 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Jaroslav Kysela <perex@...ex.cz>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     tiwai@...e.com, Bard Liao <yung-chuan.liao@...ux.intel.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: hda: Skip creating captures in SOF context



On 7/20/22 02:52, Jaroslav Kysela wrote:
> Dne 20. 07. 22 v 3:45 Kai-Heng Feng napsal(a):
>> On Tue, Jul 19, 2022 at 11:41 PM Jaroslav Kysela <perex@...ex.cz> wrote:
>>>
>>> Dne 19. 07. 22 v 16:47 Kai-Heng Feng napsal(a):
>>>> On HP laptops that use SOF driver for DMIC, the micmute LED doesn't
>>>> light up when mic is muted after commit 9b014266ef8a ("ASoC: SOF:
>>>> topology: use new sound control LED layer").
>>>>
>>>> The micmute LED itself is still working via sysfs, but it doesn't follow
>>>> mute anymore. That's because unlike vendors like Dell and Lenovo, HP
>>>> laptops use HDA codec to control mute LEDs instead of ACPI. So on HP
>>>> laptops, both SOF and HDA create captures with
>>>> SNDRV_CTL_ELEM_ACCESS_MIC_LED access, snd_ctl_led_set_state() considers
>>>> there are two different kcontrols and one of them is not muted.
>>>
>>> It does not mean that it's a wrong behavior. When both controls are muted, the
>>> LED should be turned on. It just requires that all inputs are off (and it may
>>> be the default - probably we can set in UCM or so). If you turn the "Capture
>>> Switch" off in amixer / alsamixer, do things work as expected ?
>>
>> Yes. When all captures are muted the micmute LED is on.
>>
>>>
>>>> So skip creating captures for HDA when it's called from SOF, the
>>>> captures are already handled by SOF.
>>>
>>> The capture controls are for other inputs like external analog microphone. If
>>> it is required to suppress the MIC LED for some hardware, just skip the
>>> "spec->mic_mute_led = 1" assignment in hda_generic.c . Also, the check
>>> "codec->core.type != HDA_DEV_ASOC" is not sufficient, because you don't know,
>>> if the topology really sets the MIC LED flag.
>>
>> AFAIK the external analog microphone on DMIC laptop is driven by SOF driver too.
>> If those capture controls are indeed needed for external analog mics,
>> use UCM to mute them by default won't work either.
> 
> Could you describe this ? I though that only DMIC is handled by SOF when HDA
> codec is in the system. There is a separate analog codec for external analog
> microphone or the HDA codec is somehow connected to SOF/DSP ? If so, how ?

The HDA codec is connected in the same way in all cases, there's no
hardware/electrical/routing difference.

When used, the SOF driver will handle ALL links, be they DMIC or
HDAudio. The difference for HDaudio is that instead of a single DMA
transfer (DDR->FIFO), we have a first 'Host' DMA into the DSP SRAM, some
processing and a second 'Link' DMA from DSP SRAM to the HDaudio FIFO
(reversed flow for capture).