[ltp] Re: [ibm-acpi-devel] thinkpad-acpi release 0.24-20100220 uploaded to ibm-acpi.sf.net

Henrique de Moraes Holschuh linux-thinkpad@linux-thinkpad.org
Mon, 22 Feb 2010 23:22:24 -0300

On Mon, 22 Feb 2010, Pedro Ribeiro wrote:
> The whole mess about the acpi_osi=Linux is because userspace tools
> always do a volume up / volume down, even when the volume is muted.
> The result is that the volume goes up / down and unmuted at the same
> time which is annoying.

Well, do this (I need a report with and without OSI=Linux):

"grep . /sys/bus/platform/devices/thinkpad_acpi/hotkey_*" (will cause the
kernel to complain.  It is harmless, ignore that and send me the result).

Then, find something that lists to input events, like the "input-event"
utility from Debian/Ubuntu's input-utils package.  Run two instances of it,
one bound to thinkpad-acpi's event device, and the other to the keyboard
input device.

Mute, unmute, volume up/down, etc.  Report which events show up in the
keyboard device, and which ones show up in thinkpad-acpi's device.  Make
sure to report also the mute state at which step (i.e. whether it is mute or

And BTW, does it unmute when you press mute twice?  With OSI=Linux?
Without?  In the BIOS?

> I tried to get the ALSA card working with
> modprobe thinkpad-acpi volume_control=1 volume_capabilities=1
> as well as the default parameters but the volume up/down does not
> work. The proc interface also only works for mute.

volume up/down control will *NOT* work in your thinkpad, it has only a
mute/unmute gate.  All it can do is mute/unmute in firmware, the rest is
done in the HDA mixer.

> Is it only for older models which also have volume up/down in hardware
> or for newer models also? What is the purpose of it? (please don't get
> me wrong, im just asking!)

The ALSA monitor mode is for on-screen-feedback, and will work
out-of-the-box the day userspace desktop environments decide to have proper
ALSA functionality.

The ALSA control mode effectively gives userspace (which we *know* is not to
be trusted in those matters by default ;-) ) the right to mute or unmute
your thinkpad it the worst possible moment, and in an IBM thinkpad, to make
a mess of the speaker/headphone volume as well.  Maybe you have some
creative use for it, and if you do, it is there and you can enable it.

I just know distros will enable the control mode, no matter what I say, and
break things for every IBM thinkpad user with a dock and something plugged
to the line-out output (the *only* audio output in a dock), though.

  "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