No sound with Thinkpad x130e E-450 Radeon 6320
I'm not getting any audio on my Lenovo Thinkpad x130e. I'm using the open source driver, not the proprietary one. Running lubuntu 12.10.
When I run alsamixer it initially shows "HD-Audio Generic" and only lists S/PDIF. If I hit F6 and select "HDA ATI SB" I have a lot more, such as Master, Headphone, Speaker, Mic etc... Nothing is muted and the levels are all turned up, but I get no sound.
I have searched for solutions and found a suggestion to add "radeon.audio=1" to grub, but no luck.
I just found another suggestion to install pulseaudio and pavucontrol, and that gets the sound working.
Any ideas why alsa isn't working but pulse is?