Is there a reason this is not a safe LED? It seems to fit with the on and off
capabilities of the other LEDS that are exposed through thinkpad-acpi.
Unlike speaker mute button, this does nothing in hardware.
If thinkpad-acpi offers the enablements someone could write something in
userspace (maybe a deamon or a trigger) to turn the led on and off. The issue
is that this can be done at the pulse audio level or the ALSA level. Not very
optimally to be done in the kernel level in ALSA though. Reason is you can do
your muting in userspace through pulse audio and not even bother with ALSA.
This is an example, though other sound servers could also do the same thing.
Lenovo designed it to be used under Windows. They under Windows they have a
daemon listening for the mutemic keypress. When that happens it:
1) Mutes the Windows Mixer
2) Sets LED on Microphone
* Daemon will change LED if mic mixer is unmuted on Windows mixer (not
using the button)
It ultimately is a userspace activity and it's userspace that makes sure the
LED is in a correct state for the user.
The button it's self just sends a keypress. This is finally now supported in
thinkpad-acpi:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=33009557bd
Now what is left is enablement of the LED through userspace. I believe trying
to create a large LED interface for one button on a Thinkpad is very unlikely
to happen.
Thanks,
Jerone
----- Original Message -----
From: "Henrique de Moraes Holschuh" <h...@hmh.eng.br>
To: "Jerone Young" <jyo...@redhat.com>
Cc: ibm-acpi-devel@lists.sourceforge.net
Sent: Monday, November 7, 2011 5:57:29 PM
Subject: Re: [ibm-acpi-devel] [PATCH] Add LED support for mic mute button
On Mon, 07 Nov 2011, Jerone Young wrote:
> Back in May Andy Lutomirski submitted a patch to add mic mute button
> functionality to thinkpad acpi. It appears that the only issue is that
> it was submitted to the wrong list, and got caught up in kernel.org/Alsa
> discussion of standardize the naming scheme.
All I ask is that people with access to other thinkpads test that led so
that we know it is really the mic led on all thinkpads with a mic, and not
something else in the other Lenovo thinkpads.
That said, the MIC led is NOT a safe LED. You do NOT want for it to be easy
to lie to you that the MIC is off when it is not off.
As far as I know, unlike the cellphone industry, *we* are not in the
business of making it trivial to random third-parties to turn the devices we
write the operating system for into stealth spy drones.
> The disscussion can be found here:
> http://comments.gmane.org/gmane.linux.drivers.platform.x86.devel/1962
I'm not amused. We have LED triggers for a reason, ALSA should provide a
generic set of useful LED triggers hooked to the standard mixer controls,
and I'd be happy to hook them to the platform LEDs.
Userspace should not be in the loop for something like this, unless there
really is no other way.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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