[Bug 94825] LVDS blank screen on GM45

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Tue Apr 5 12:08:50 UTC 2016


https://bugs.freedesktop.org/show_bug.cgi?id=94825

Ville Syrjala <ville.syrjala at linux.intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |NEEDINFO

--- Comment #4 from Ville Syrjala <ville.syrjala at linux.intel.com> ---
OK. That's interesting. The BIOS panel list clearly matches the VBT timings
list 1:1 (except the 1400x1050 being shown as reserved in the BIOS). However
the VBT panel_type is still 2. For some reason it always seems to be 2 on all
the machines I see, and I'm really starting to wonder if we're parsing it
correctly.

Could you change the panel type in the BIOS to something else, and then grab
another copy of i915_opregion so that we can check what (if anything) changes
in the VBT?

Also another thing I'd like to see is what the VBIOS puts into the scratch
registers. So can you also run the following commands with two different panel
types selected in the BIOS so that we can see if the scratch registers change:
intel_reg read --count 16 0x70410
intel_reg read --count 16 0x71410
intel_reg read --count 3 0x72414

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