[pulseaudio-discuss] ThinkPad T-510 audio output mute LED non-workingness

[Raymond Yau]

> > in response to the event.  What action can be taken to turn on the mute
> LED?
> > Issue an amixer/pactl/pacmd command to toggle the Master Playback mute
> state?
>
> Speaking as the thinkpad-acpi driver maintainer: Keeping the ThinkPad MUTE
> LED states in sync is the kernel's job. This is the beginning and the end
> of it.
>
> It clearly is not working properly right now.  Possibly the defect is
> restricted to some thinkpads: Lenovo changes firmware behaviour sometimes.
> They're good about leaving a knob you can set to get whatever behaviour you
> want/need.  They're not always that good about _testing_ it, though.  And
> we (kernel side) are not that good at either knowing the behaviour exists,
> or making use of it.
>
> Or it might be a simple driver bug that affects every thinkpad with a mute
> LED. I hope so, because that's much easier to fix.
>
> Those are the facts.  It doesn't look like there is anything pulse-audio
> related in this issue:  it is a matter for the kernel to fix. Either in the
> ALSA sublayer, if it is not being able to correctly signal thinkpad-acpi to
> change Mute LED state, or in thinkpad-acpi if it is not correctly relaying
> to the thinkpar firmware the desired mute LED state.
>
> > No, that won't do it, because the LED isn't following the mixer mute
> state
> > (see earlier posts in this thread).  Directly access the LED via some
> exposed
> > interface to it?  No sign that any such any such interface is available
> in
> > /proc/acpi or /sys/class/leds (see comment #15 in the kernel bugtracker).
>
> And it is not going to be made available (in some thinkpads, it cannot
> even be done: when you change the hardware mute gate state, the EC updates
> the LED state to match).  This is why we will consider any mute led
> misbehavior to be a kernel issue, to be fixed in the kernel.
>
> > As I mentioned on the kernel bugtracker, I'm going to take this up with
> the
> > thinkpad ACPI folks, see if they have any suggestions.
>
> I lack the hardware to develop-and-test a fix (I am long overdue for a
> replacement thinkpad, really. I only have a good T43, and a damaged R60),
> but I am open to help (and ACK kernel-side patches).
>
> --
>

http://support.lenovo.com/us/en/documents/migr-58317

T43 seem using snd-intel8x0 AC97 codec AD1981B

https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/sound/pci/hda/thinkpad_helper.c?id=b317b032d2dcb5e518cc9630cc6f1c7c24afedfc

The mute led and mic led only supported by those HDA codecs (Realtek and
Connexant) which use hda/thinkpad_helper.c

https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/log/sound/pci/hda/patch_analog.c?qt=grep&q=thinkpad

Those thinkpads using ADI HDA codecs are not affected by the above patch


http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/platform/x86/thinkpad_acpi.c?id=420f9739a62cdb027f5580d25c813501ff93aa6f

as tpacpi_led_set is always exported by thinkpad-acpi, only thinkpad_acpi
module know whether "ssms" interface is available or not

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/platform/x86/thinkpad_acpi.c?id=9a417ec0c9d1f7af5394333411fc4d98adb8761b


Should thinkpad_acpi only disable EC console only when either "SSMS" or
"MMTS" is available ?
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