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

Raymond Yau superquad.vortex2 at gmail.com
Tue Apr 21 01:19:17 PDT 2015

> The main thing to note is that in 3.18, when the driver fielded the mute
> key events itself, it handled those events by toggling the state of a
> low-level hardware-based mute switch (upper right dotted box). This HW
> evidently applied only to the speaker, not headphones, and seems to have
> relationship to the pavucontrol/pactl/amixer mixer-based mute.  Also --
> central to the issue here -- invoking the HW mute function via the mute
> also toggled the mute LED, and that LED state always faithfully reflected
> the actual mute state (LED on == speaker audio off, always).  In the other
> direction, there was never any observed effect on the mute LED state as a
> result of toggling the mixer-based Master Playback mute, via pavuconrol,
> pactl, pacmd, or amixer (or in any other way that I ever found). In short,
> the mute LED in 3.18 seems like it's solely under control of the mute key
> event as fielded by the driver.
> In 3.19, the mute key is no longer fielded directly by the driver; it
> simply an ordinary userspace key. That was an intentional change and
> not a bug. But the point is that in 3.19, if the user wishes to perform
> in userspace (e.g., by "pactl"ing the mixer mute function in response to a
> mute key event, or by clicking the pavucontrol mute icon, or by issuing an
> amixer or pactl command) it's not going to have the same effect that the
> driver used to realize in 3.18, in two ways: One is relatively minor, and
> the other is central to the issue here:
>   * First, and obviously, it isn't going institute the mute function via
>     HW mute, but rather via the mixer-based Master Playback mute. This in
>     itself is probably no big deal: There are some minor functional
>     between the HW mute and the mixer mute, but most users won't care and
>     it's probably not a very important issue. Let's ignore it here.
>   * Second -- and here is the real issue -- since the mixer-based Master
>     Playback mute has (and never had, even in 3.18) any effect on the mute
>     LED (on my T-510) the mute LED does not follow the mixer-based mute
>     state. It's always off. There just doesn't seem to be any way turn on
>     the mute LED via pavucontrol, pactl, pacmd, or amixer.
> The second item is the real head-scratcher: Not only is the functionality
> the mute LED lost in 3.19 (on my T-510 at least) but it is David's
> that the LED _ought_ to be following the Master Playback mixer mute state,
> yet it does not.

Apr 16 15:56:17 ga kernel: thinkpad_acpi: ThinkPad ACPI Extras v0.25
Apr 16 15:56:17 ga kernel: thinkpad_acpi: http://ibm-acpi.sf.net/
Apr 16 15:56:17 ga kernel: thinkpad_acpi: ThinkPad BIOS 6MET81WW (1.41 ),
EC 6MHT43WW-1.18
Apr 16 15:56:17 ga kernel: thinkpad_acpi: Lenovo ThinkPad T510, model
Apr 16 15:56:17 ga kernel: thinkpad_acpi: detected a 16-level brightness
capable ThinkPad
Apr 16 15:56:17 ga kernel: thinkpad_acpi: radio switch found; radios are
Apr 16 15:56:17 ga kernel: thinkpad_acpi: This ThinkPad has standard ACPI
backlight brightness control, supported by the ACPI video driver
Apr 16 15:56:17 ga kernel: thinkpad_acpi: Disabling thinkpad-acpi
brightness events by default...
Apr 16 15:56:17 ga kernel: thinkpad_acpi: Standard ACPI backlight interface
available, not loading native one
Apr 16 15:56:17 ga kernel: input: ThinkPad Extra Buttons as


Let user know whether the mute led or mic led interface is supported by
tpacpi_led_set() when thinkpad_acpi is loaded

static int mute_led_init(struct ibm_init_struct *iibm)
acpi_handle temp;
int i;

for (i = 0; i < TPACPI_LED_MAX; i++) {
struct tp_led_table *t = &led_tables[i];
- if (ACPI_SUCCESS(acpi_get_handle(hkey_handle, t->name, &temp)))
+ if (ACPI_SUCCESS(acpi_get_handle(hkey_handle, t->name, &temp))) {
+        pr_info("Thinkpad led %s interface supported.\n", t->name);
mute_led_on_off(t, false);
+    }
t->state = -ENODEV;
return 0;
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