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

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Date:   Wed, 20 Jul 2022 08:29:15 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     Jaroslav Kysela <perex@...ex.cz>, tiwai@...e.com,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...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, 20 Jul 2022 03:45:37 +0200,
Kai-Heng Feng wrote:
> 
> 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.
> 
> Skip "mic_mute_led = 1" can be hard because it's still needed for legacy HDA.
> If checking "HDA_DEV_ASOC" isn't sufficient, is it possible to just
> check "card" in snd_ctl_led_set_state(), instead of kcontrols?
> I think it's reasonable to assume a card has just one speaker LED and
> one microphone LED.

Hm, but skipping the whole create_capture_mixers() call doesn't sound
right, either.  I thought there are still external mic controls via
codec, and those would be skipped by this patch?

If the mic-mute LED is the problem, it should be rather checked in the
caller of snd_hda_gen_add_micmute_led_cdev(), i.e. patch_realtek.c,
instead, IMO.


thanks,

Takashi