I have a X240 (without any dock), and in Linux 3.17.4, I used to have - "Speaker" with switch and volume bar (in alsamixer), - "PCM" with switch and volume bar, - the headphone output volume would be controlled by both Master and PCM.
With 3.18.1, bisected down to below commit, this all went bonkers. - "Speaker" has only a switch but no volume bar, - speakers do not output _any_ sound whatsoever anymore - changing the PCM volume does not affect either Headphone or Speaker.
commit 7c21539c45eace48e9f6fbdd59347d8416960af5 Author: Lukas Bossard mr.bobukas@gmail.com Date: Wed Oct 29 18:31:07 2014 +0100
ALSA: hda - Add ultra dock support for Thinkpad X240.
Adding ultra doch support for Lenovo Thinkpad X240 (17aa:2214). [Actually replaced the entry with ALC292_FIXUP_TPT440_DOCK -- tiwai]
Reverting this commit on top of v3.18.1 restores the sought functionality.