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

Hui Wang hui.wang at canonical.com
Mon Mar 30 20:51:17 PDT 2015

On 03/31/2015 05:54 AM, Glenn Golden wrote:
> HW: ThinkPad T-510, x86_64
> SW: Arch Linux (synched within a week) kernel = 3.19.2, PA 6.0
> On the above setup, the mic mute function (invoked via pavucontrol) works as
> expected: Click the mute icon, it mutes the mic input, indicates the muted
> state by greying out the pavucontrol mic gain control, and illuminates the
> little LED on the mic mute button.
> But the analogous functionality for muting audio output only does the
> first two things, and has no effect on the mute LED. (The LED is always off.)
>  From googling around, I'm pretty sure that these two particular LEDs are not
> directly under user control (e.g. via ACPI) but are somehow bound to the
> mute/unmute functionality in the snd-hda-intel driver. This understanding is
> based on kernel posts like this:
>      https://bugzilla.kernel.org/show_bug.cgi?id=49391
> and other similar ones.
> Before filing a ticket with the kernel guys, wanted to ask if this
> function-LED binding is in any way under control of pulseaudio itself?
> In other words, I guess what I'm asking is whether pulseaudio just tells
> the driver to "mute the audio", and the driver sets the LED state accordingly,
> or whether pulse tells the driver separately to "mute the audio" and also
> "turn on the LED".
According to my understanding, it should be the former one,  PA tells 
the driver to "mute the audio", and the driver sets the LED accordingly.
> Knowing the answer to this, I can post a more informative ticket to the
> kernel guys. (Or maybe the fix is even in pulseaudio itself?)
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