[Intel-gfx] Bug - DP monitor does not get activated when snd_hda_intel is loaded

Daniel Martin consume.noise at gmail.com
Mon Mar 3 11:15:56 CET 2014


I'm having a bug here, where the loaded hda (snd_hda_intel) module
causes some (timing?) problem resulting in a monitor connected to the DP
not to get active. I can reproduce this on a Lenovo X201 and T410
(Ironlake) sitting on a docking station, which has a monitor (Dell
U2410) connected to a DP.

First, I tried it on alsa-devel, but Takashi send me here. (This message
has just marginally changed.)

Steps to reproduce:
1. boot with the laptop at the docking station and the monitor plugged in
2. start the X-Server
   ... output on LVDS and DP is okay
3. disable the DP: xrandr --output LVDS1 --preferred --output DP1 --off
   ... output on LVDS - okay
4. switch to DP: xrandr --output LVDS1 --off --output DP1 --preferred
   ... DP _usually_ doesn't gets active, it turns off into suspend state

If I boot a kernel without the hda module step 4 always works. When
having the hda module loaded I need some luck and some iterations of
step 3 and 4 to activate the monitor at the DP.

I verified that the problem exists in kernel v3.13.1 and v3.14-rc4.

The logs I have attached have been created on the T410 with kernel
v3.14-rc4. The first alsa-info....txt has been created right after
booting, the second one after step 4 failed. The kernel has been build
with all alsa debug options I could find, the config is attached as
well, and the kernel has been booted with drm.debug=0xe.

I hope that anyone can read something usefull - something that went
wrong - out of the log files. My unexercised eye can't spot anything

If more logs are necessary, I'll send them.

    Daniel Martin

PS: Should I open a fdo bug for drm/intel?
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