linux-kernel - Re: [PATCH v3 3/3] ALSA: hda: add support for Huawei WMI micmute LED

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Message-ID: <20181123220523.GA22118@amd>
Date:   Fri, 23 Nov 2018 23:05:23 +0100
From:   Pavel Machek <pavel@....cz>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Ayman Bagabas <ayman.bagabas@...il.com>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        Hui Wang <hui.wang@...onical.com>,
        Andy Shevchenko <andy@...radead.org>,
        Darren Hart <dvhart@...radead.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Kailang Yang <kailang@...ltek.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] ALSA: hda: add support for Huawei WMI micmute LED

HI!

> > > > > > > You have general-purpose LED, yet you are treating it as "something
> > > > > > > special". That means ugly code (quoted above) and lack of flexibility.
> > > > > > >
> > > > > > > For example, if my notebook lacks HDD LED, I can use scrollock LED for
> > > > > > > that instead. Or, in reverse way, maybe "mic mute" LED is not useful
> > > > > > > for me, and I'd like to use it for notifications instead.
> > > > > >
> > > > > > I'm not against adding the LEDs device implementation for any exotic
> > > > > > usage.
> > > > > >
> > > > > > But for the audio mute LED features, you'll need really lots of other
> > > > > > works if it were implemented via leds device.  That's the hardest
> > > > > > part, and a few lines of hooks solves it easily in the kernel side.
> > > > > > That's all about it.
> > > > > >
> > > > > > If you are ready for submitting the real solutions in user-space side
> > > > > > (patching PulseAudio and whatever all existing sound daemons, and
> > > > > > creating yet another daemon for non-PA systems (another footprint,
> > > > > > lovely), and so on), we can happily delete such in-kernel hooks :)
> > > > >
> > > > > I'm not saying we should move it to the userspace.
> > > > >
> > > > > I'm saying this should be "normal" led. drivers/leds/led-huawei-acpi.c,
> > > > > or something. Perhaps this acpi stuff is so similar you don't really
> > > > > need .c code.
> > > > >
> > > > > And then there should be a "mic muted" trigger. Similar to
> > > > > drivers/leds/trigger/ledtrig-disk.c.
> > > >
> > > > And who will trigger this, e.g. when the mixer is muted?
> > > 
> > > Is this settled? I'm encouraged to promote this series to our for-next branch.
> > 
> > I'd prefer this to be normal LED and "mic muted" to become normal
> > trigger.
> 
> But how would you solve the existing problem?
> 
> As already mentioned, you'll need to hook the LED trigger and the
> actual mixer value change.  This is the biggest missing piece, and
> it's the very reason we have the exported symbol from the platform
> driver side.
> 
> So, if you prefer in that way, please implement that for the existing
> driver (thinkpad_acpi and dell-laptop) at first.  I'll be really happy
> to get rid of the present ugly solution!  But it's been there just
> because it's not so trivial at all.  FWIW, this must be all done
> inside the kernel; otherwise you'll hit a regression.

I am really have enough work to do at the moment, but let me take a look.

> If the path via leds class can't be achieved quickly, I'd prefer
> taking the current approach at first.  Once after it's done for those
> above, we can apply the same for huawei-wmi later, too.

I'd prefer not adding more mess. Don't expect full solution from me,
but ... I should have something better than what is in the tree rather
soon.

Best regards,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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