[ltp] Re: T420 Mute LED

Marius Gedminas linux-thinkpad@linux-thinkpad.org
Wed, 12 Mar 2014 10:42:28 +0200

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On Wed, Mar 12, 2014 at 09:19:53AM +0100, Paul Bolle wrote:
> On Wed, 2014-03-12 at 08:53 +0200, Marius Gedminas wrote:
> > On Sun, Mar 09, 2014 at 09:58:34PM -0700, Peter FP Zhang wrote:
> > > T420 Mute/UnMute and its LED handling can not be controlled by event =
mask or
> > > other.
> > > Mute button event is reported to BIOS from embedded controller and BI=
> > > processed it by itself to apply the mute setting  and LED. There is no
> > > interface to manage them.
> >=20
> > Is that really a good idea?  When I mute the speaker using software, the
> > state of the LED doesn't change.  After that, if I use the button, the
> > LED shows the opposite of the actual mute state.
> >=20
> > (X220 here, but I'm assuming the same design.)
> Also X220 (Fedora 20, Gnome 3.10.y, kernel 3.13.y):
> - fiddling with a slider in the top right pop-up-control-area (what's
> its current name?): LED does change;
> - fiddling with volume buttons (next to the mute button): mute LED turns
> off if volume goes up, mute LED turns on _very_ shortly if volume
> reaches lowest state (ie, it flashes but doesn't stay on).

You're right!  I observe the same thing now.

It's possible the BIOS upgrade I did earlier this year fixed this, and I
simply didn't notice (since I trained myself not to pay attention to the
lying LED ;).

Marius Gedminas
As an aside, isn't one of the good things about Lisp that with it
one plays with a _language_, while with C one plays with a _machine_
(and with C++ one---well, is engaged in non-playful activities with
a machine).
        -- Vassil Nikolov

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