linux-kernel - Re: disabling CONFIG_LED

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Date:   Tue, 13 Oct 2020 22:07:45 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Udo van den Heuvel <udovdh@...all.nl>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-leds@...r.kernel.org, Dan Murphy <dmurphy@...com>,
        Pavel Machek <pavel@....cz>
Subject: Re: disabling CONFIG_LED_CLASS

On 10/13/20 9:56 PM, Udo van den Heuvel wrote:
> On 14-10-2020 06:49, Randy Dunlap wrote:
>> If you disable SND_HDA_CODEC_REALTEK, then the rest of the
>> LED kconfig symbols can be disabled.
> 
> Sure,
> 
> but:
> 
> # dmesg|grep audi
> (...)
> 
> [   19.971537] snd_hda_codec_generic hdaudioC0D0: ignore pin 0x7, too
> many assigned pins
> [   19.973547] snd_hda_codec_generic hdaudioC0D0: autoconfig for
> Generic: line_outs=0 (0x0/0x0/0x0/0x0/0x0) type:line
> [   19.975642] snd_hda_codec_generic hdaudioC0D0:    speaker_outs=0
> (0x0/0x0/0x0/0x0/0x0)
> [   19.977774] snd_hda_codec_generic hdaudioC0D0:    hp_outs=0
> (0x0/0x0/0x0/0x0/0x0)
> [   19.980176] snd_hda_codec_generic hdaudioC0D0:    mono: mono_out=0x0
> [   19.982257] snd_hda_codec_generic hdaudioC0D0:    dig-out=0x3/0x5
> [   19.984412] snd_hda_codec_generic hdaudioC0D0:    inputs:
> [   20.035088] snd_hda_codec_realtek hdaudioC1D0: autoconfig for
> ALC1220: line_outs=3 (0x14/0x15/0x16/0x0/0x0) type:line
> [   20.036940] snd_hda_codec_realtek hdaudioC1D0:    speaker_outs=0
> (0x0/0x0/0x0/0x0/0x0)
> [   20.039579] snd_hda_codec_realtek hdaudioC1D0:    hp_outs=1
> (0x1b/0x0/0x0/0x0/0x0)
> [   20.041690] snd_hda_codec_realtek hdaudioC1D0:    mono: mono_out=0x0
> [   20.044076] snd_hda_codec_realtek hdaudioC1D0:    dig-out=0x1e/0x0
> [   20.046173] snd_hda_codec_realtek hdaudioC1D0:    inputs:
> [   20.049252] snd_hda_codec_realtek hdaudioC1D0:      Front Mic=0x19
> [   20.051287] snd_hda_codec_realtek hdaudioC1D0:      Rear Mic=0x18
> [   20.053084] snd_hda_codec_realtek hdaudioC1D0:      Line=0x1a
> [   20.427487] usbcore: registered new interface driver snd-usb-audio
> 
> I.e.: it looks like I will lose some funcionality when I disable
> SND_HDA_CODEC_REALTEK.

OK. At present you can't have it both ways, i.e., SND_HDA_CODEC_REALTEK
with no LEDS. That driver apparently wants LEDS.

According to this commit:

commit 7cdf8c49b1df0a385db06c4f9a5ba1b16510fdcc
Author: Takashi Iwai <tiwai@...e.de>
Date:   Thu Jun 18 13:08:31 2020 +0200
    ALSA: hda: generic: Add a helper for mic-mute LED with LED classdev

the Realtek and other drivers need LED support:

"""
    Also, introduce a new kconfig CONFIG_SND_HDA_GENERIC_LEDS, to indicate
    the usage of mute / mic-mute LED helpers.  It's selected by the codec
    drivers (Realtek, Conexant and Sigmatel), while it selects the
    necessary LED class dependencies.
"""


-- 
~Randy