On Thu, 16 Oct 2014, Andy Lutomirski wrote:
ThinkPads have hardware volume controls and three buttons to control them. (These are separate from the standard mixer.) By default, the buttons are:
- Mute: Mutes the hardware volume control and generates KEY_MUTE.
- Up: Unmutes, generates KEY_VOLUMEUP, and increases volume if applicable. (Newer thinkpads only have hardware mute/unmute.)
- Down: Unmutes, generates KEY_VOLUMEDOWN, and decreases volume if applicable.
On IBM ThinkPads, the "generates KEY_foo" thing is controlable by the driver. In fact, thinkpad_acpi defaults to NOT send these, all breakage is entirely the fault of userspace that enables it instead of doing OSD out of the extra mixer, and then fails to deal with the side-effects.
On Lenovo ThinkPads, it depends on BIOS/EC version for the X60/T60. Later versions will behave like the X61/T61. Since family 200 you can tell the EC to switch modes (latch, toggle, none), but Lenovo didn't test it well enough.
This behavior is unfortunate, since modern userspace will also handle the hotkeys and change the other mixer. If the software
Like I said, we disable that by default, and userspace enables them back because they want to use it as a keyboard. We could override it entirely on the IBM thinkpads, and refuse to issue any key events no matter what, I suppose.
This should also allow us to remove _OSI(Linux) for all ThinkPads.
No, it doesn't. Only after an exaustive search for what _OSI(Linux) changes across a brickload of thinkpad ACPI dumps could we say that for sure.
For future reference: It turns out that we can ask ACPI for one of three behaviors directly on very new models. They are "latch" (the default), "none" (no automatic control), and "toggle" (mute unmutes when muted). All of the modes besides "none" seem to be a bit buggy, though, and there is no known way to get any notification that the hardware state has changed other than listening for a mute button press on the i8042 port.
Yeah.
- The EC or perhaps SMM firmware can optionally automatically change
- the volume in response to user input. Unfortunately, this rarely
It is the EC, which also emulates the i8042 KBC.
I don't see any problems with the code, will have to test it in a IBM thinkpad, though (I have one).