The DP monitor connected to a dock port of HP EliteBook 940 G1 doesn't work any longer since 4.2 kernel. It worked with 4.1. When connected, it results in repeated errors of [drm:intel_dp_start_link_train [i915]] *ERROR* too many voltage retries, give up eventually got many other errors and warnings. The git bisection pointed to the commit 8504c74c7ae48b4b8ed1f1c0acf67482a7f45c93 drm/i915: Preserve ddi_pll_sel when allocating new pipe_config and actually reverting this commit makes DP working again. IIRC, it's MST.
Created attachment 186651 [details] dmesg from broken 4.2 kernel at plugging DP
Created attachment 186661 [details] dmesg from 4.2 kernel with revert after plugging DP
Created attachment 186671 [details] dmesg from 4.1.6 kernel after plugging DP
Oh, BTW it's a Hawell ULT GT2 mobile. 00:02.0 0300: 8086:0a16 (rev 0b) (prog-if 00 [VGA controller]) DeviceName: 128 Subsystem: 103c:213e X intel driver is 2.99.917. Mesa 10.6.5. libdrm 2.4.64.
http://lists.freedesktop.org/archives/intel-gfx/2015-August/074788.html
Which git branch is supposed to have the fix?
Looks to be in drm-intel-next-fixes.
OK, thanks, I'll give it a try tomorrow. (I already tried drm-intel-fixes and drm-intel-next yesterday, but it failed, too.)
commit 7e6313a2516dbcd168f4ae36f0abe1a9227106b5 Author: Ville Syrjälä <ville.syrjala@linux.intel.com> Date: Tue Aug 11 20:21:46 2015 +0300 drm/i915: Don't use link_bw for PLL setup commit 6fa2d197936ba0b8936e813d0adecefac160062b Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> Date: Mon Aug 31 11:23:28 2015 +0300 i915: Set ddi_pll_sel in DP MST path (The first is just to avoid conflicts.)
I confirmed that the DP works again with drm-intel-next-fixes branch. Thanks! However, there are still a few ugly warnings. At booting: [ 5.205358] [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in has_drrs (expected 1, found 0) [ 5.205361] ------------[ cut here ]------------ [ 5.205387] WARNING: CPU: 3 PID: 76 at drivers/gpu/drm/i915/intel_display.c:12691 intel_modeset_check_state+0x5a4/0x870 [i915]() [ 5.205388] pipe state doesn't match! At plugging DP: [ 33.096865] [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in has_drrs (expected 1, found 0) [ 33.096876] ------------[ cut here ]------------ [ 33.096916] WARNING: CPU: 3 PID: 988 at drivers/gpu/drm/i915/intel_display.c:12691 intel_modeset_check_state+0x5a4/0x870 [i915]() [ 33.096919] pipe state doesn't match! and [ 33.230467] WARNING: CPU: 3 PID: 988 at drivers/gpu/drm/i915/intel_display.c:6330 intel_modeset_check_state+0x112/0x870 [i915]() [ 33.230472] attached crtc is active, but connector isn't At unplugging DP: [ 218.764695] [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in has_drrs (expected 1, found 0) [ 218.764706] ------------[ cut here ]------------ [ 218.764739] WARNING: CPU: 3 PID: 988 at drivers/gpu/drm/i915/intel_display.c:12691 intel_modeset_check_state+0x5a4/0x870 [i915]() [ 218.764741] pipe state doesn't match! Should I open another bug or can we continue here?
(In reply to Takashi Iwai from comment #10) > I confirmed that the DP works again with drm-intel-next-fixes branch. > Thanks! Thanks for testing. > However, there are still a few ugly warnings. ... > Should I open another bug or can we continue here? Please file a new bug.
Opened bug 104041 for the rest.