Ubuntu
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  1. Bug #1265544
  2. Comment #56

Comment 56 for bug 1265544

Revision history for this message
In , Alberto Aguirre (albaguirre) wrote :

Created attachment 91970
Test ignoring bpp clamping

I have an ASUS UX302LA laptop running Ubuntu 14.04 daily build. I've switched the kernel to the latest drm-intel-nightly from here:

    http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/current/)

Any sequence that turns off/on the panel (suspend/resume, modesetting) results in a blank screen.

I narrowed it down to the clamping code in intel_dp.c after going through this old bug thread (see attached patch)

   https://bugzilla.kernel.org/show_bug.cgi?id=59841

When ignoring the clamping - no blank screen issues occur.

The hack implemented in intel_dp.c:

   commit c6cd2ee2d59111a07cd9199564c9bdcb2d11e5cf
   Author: Jani Nikula <email address hidden>
   Date: Mon Oct 21 10:52:07 2013 +0300W

       drm/i915/dp: workaround BIOS eDP bpp clamping issue

Is not effective on the UX302LA/LG - from logs it looks like intel_dp_get_config is never called - any idea why?