Ubuntu
linux package

  1. Bug #1275794
  2. Comment #42

Comment 42 for bug 1275794

Revision history for this message
In , Consume-noise-7 (consume-noise-7) wrote :

Created attachment 89947
dmesg 3.11 (working! - with preemption)

I've found that the option "Preemptible Kernel (Low-Latency Desktop)" can be used as a workaround for the problem. It doesn't work always, but usually. Tested with v3.9..v3.11.

In the dmesg I can see the call to intel_dp_set_signal_levels() and a few others, which I don't without preemption (attachment 89906). So, I guess the lack of it before a call to ironlake_panel_vdd_work() is the bug?

As of v3.12 this workaround doesn't work anymore. I've started to bisect it, but stopped as it was to inaccurate (as stated above, it didn't worked always for v3.9..v3.11) and time consuming. And imo it's not that predictable/representable due to preemption anyways. But, if you think that it's worth looking at it, then I could try to completly bisect it.