Bug 52601
| Summary: | [eDP vs LVDS PP fights] Blank screen when booting 3.8-rc3 | ||
|---|---|---|---|
| Product: | Drivers | Reporter: | Ryan Coe (nismoryco) |
| Component: | Video(DRI - Intel) | Assignee: | Jani Nikula (jani.nikula) |
| Status: | RESOLVED PATCH_ALREADY_AVAILABLE | ||
| Severity: | normal | CC: | daniel, intel-gfx-bugs |
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 3.8-rc3 | Subsystem: | |
| Regression: | Yes | Bisected commit-id: | |
| Attachments: |
lspci output
drm debug output from dmesg Kernel bisection log drm/i915/eDP: do not write power sequence registers for ghost eDP dmesg |
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Please boot with drm.debug=0xe added to your kernel cmdline and grab the complete dmesg via ssh. Created attachment 91081 [details]
drm debug output from dmesg
Created attachment 91271 [details]
Kernel bisection log
I tried to do some more digging with git bisect. I believe that 82ed61fa1a4e08d5f9e86fb1b715b50ed678b6ac is the first commit that causes the problem.
The machine seems to have a ghost eDP while the panel is LVDS. intel_dp_init_connector() sets up panel power sequencing based on eDP VBT data before noticing it's a ghost. (And, indeed, the machine seems to have an eDP blob in the video BIOS.) The change in the bisected commit is that it starts writing back the values to the power sequencing registers. The panel control port select bits of PP_ON_DELAYS are likely the critical part, screwing up LVDS. As a side note, it would probably be sane to clean up intel digital port and intel connector in intel_dp_init() if intel_dp_init_connector() fails. Created attachment 91351 [details]
drm/i915/eDP: do not write power sequence registers for ghost eDP
Ryan, please try the attached patch.
Created attachment 91361 [details]
dmesg
That patch seems to have cleared the problem. I have attached my current dmesg with drm.debug output still on in case you want to look at it. Thank you.
Thanks, patch submitted for inclusion. Merged to -fixes: commit f30d26e468322b50d5e376bec40658683aff8ece Author: Jani Nikula <jani.nikula@intel.com> Date: Wed Jan 16 10:53:40 2013 +0200 drm/i915/eDP: do not write power sequence registers for ghost eDP |
Created attachment 91051 [details] lspci output I am getting a blank screen during booting. The system seems to be starting normally (I can hear the welcome sound in LightDM and I can access the machine via ssh). Setting 'nomodeset' in /etc/default/grub will get the screen working, but I lose the ability to adjust brightness. This is a regression from 3.7.