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

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Date:   Mon, 15 Aug 2022 15:55:16 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     Jaroslav Kysela <perex@...ex.cz>, 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 Wed, Jul 20, 2022 at 9:31 PM Pierre-Louis Bossart
<pierre-louis.bossart@...ux.intel.com> wrote:
>
>
>
> 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).

So is this approach sufficient for this issue? Or should I explore
other possibilities?

Kai-Heng

>