Created attachment 54966 [details]
Platform: IvyBridge(chief river)
Bug detailed description:
Every time I start the system with a monitor ,the edp can't light up,but if we boot with no other monitor,the EDP can work ,then plug in a monitor,the edp and the monitor all can work well.
*** Bug 44515 has been marked as a duplicate of this bug. ***
Created attachment 56177 [details] [review]
fixup dp bpc calculations
Can you please try this patch?
(In reply to comment #2)
> Created attachment 56177 [details] [review] [review]
> fixup dp bpc calculations
> Can you please try this patch?
I have try this patch with latest drm-intel-testing,the issue still occurs.
If I change the BIOS settings to use the LFP as the default VBIOS display, then I can boot with external graphics plugged in and things work.
I wonder if the BIOS on this machine is changing some display muxes around on the board at boot which prevents us from driving the eDP panel in some configs.
We'll have to test with a real system to verify.
Yeah, indeed when I set LFP display as default, the issue is gone.
Figured out the root cause of this one finally. It appears that the BIOS on the SDV doesn't set the panel power sequencing timing registers to valid values in the non-LFP case. So when we try to boot with external monitors attached, we can never power up the panel.
I also found an issue with backlight control; in the eDP case we don't try setting the CPU backlight control regs or switch the PCH to override the CPU backlight controller...
Looks like a BIOS bug in the SDVs. I posted a patch to at least sanity check the panel PPS regs so we won't see an eDP output in that case.
A patch referencing this bug report has been merged in Linux v3.5-rc1:
Author: Jesse Barnes <email@example.com>
Date: Tue Apr 10 11:58:04 2012 -0700
drm/i915: check PPS regs for sanity when using eDP
A patch referencing a commit referencing this bug report has been merged in Linux v3.8-rc1:
Author: Daniel Vetter <firstname.lastname@example.org>
Date: Sat Oct 20 20:57:41 2012 +0200
drm/i915: make edp panel power sequence setup more robust
A patch referencing a commit referencing this bug report has been merged in Linux v3.8-rc5:
Author: Jani Nikula <email@example.com>
Date: Wed Jan 16 10:53:40 2013 +0200
drm/i915/eDP: do not write power sequence registers for ghost eDP
on Jun 26, 2016 at 17:10:27.
(provided by the Example extension).