At Wed, 20 May 2015 16:31:55 +0200, Martin Steigerwald wrote:
Hello!
On ThinkPad T520 (Intel Sandybridge) with 4.14-rc4 + two BTRFS patches and one Intel P-State debug patch I have no sound output on internal Intel HD audio codec.
According to ThinkPad T520 LED with striked-through speaker the loud speaker is in disabled state. Also KDE´s Phonon says a soundcard is missing. In alsa-mixer I see nothing as MM for muted. If I press the key next to the LED I get a notification on the desktop that loud speaker has been enabled / disabled, but the LED still is on for it being disabled.
I do not hear anything in Amarok or with aplay. alsa-mixer sound volumes are 100 for master and PCM. I also tried with disabling "Auto-Mute Mod", but still no sound.
When I reboot and in BIOS or GRUB press the key then the LED toggles state.
When I reboot into Linux 4.0.1 sound is working fine and loud speaker disabled LED is toggled off, so I bet this is a regression 4.1-rc4 compared to 4.0.1.
Please run alsa-info.sh at both working and non-working cases (with old and new kernels), and attach the outputs. Run the script with --no-upload option.
Also, such a problem is rather the device permissions problem. Check the device permissions of /dev/snd/* files (also check getfacl /dev/snd/*, too).
Takashi