[alsa-devel] hda: Bug - (timing?) problem causes DP monitor to not get activated

Daniel Martin consume.noise at gmail.com
Fri Feb 28 11:47:27 CET 2014


I'm having a bug here, where the loaded hda 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.

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 turn off into suspend state

Why I think that it is related to the hda module? 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 - this might be
to much, but it shows pretty clear when the outputs have been switched.

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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: problem_with_dp_and_hda.tar.xz
Type: application/x-xz
Size: 37584 bytes
Desc: not available
URL: <http://mailman.alsa-project.org/pipermail/alsa-devel/attachments/20140228/a3966b63/attachment-0001.xz>

More information about the Alsa-devel mailing list