[Bug 103347] [dp] intel_dp.c:1554 WARN_ON(len <=8)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=103347

--- Comment #27 from shashank.sharma at intel.com <shashank.sharma at intel.com> ---
Here is your VBT setting:
[drm:intel_bios_init] Port A VBT info: DP:1 HDMI:0 DVI:0 EDP:0 CRT:0
[drm:intel_bios_init] VBT HDMI level shift for port A: 8
[drm:intel_bios_init] Port B VBT info: DP:1 HDMI:1 DVI:1 EDP:0 CRT:0
[drm:intel_bios_init] VBT HDMI level shift for port B: 8
[drm:intel_bios_init] Port C VBT info: DP:0 HDMI:1 DVI:1 EDP:0 CRT:0
[drm:intel_bios_init] VBT HDMI level shift for port C: 8

This means this is how connector allocation will go:
DP-1: PORT A
DP-2: PORT B
HDMI-A-1: PORT B
HDMI-A-2: PORT C

And also port B has LSPCON:
[drm:intel_ddi_init] VBT says port B has lspcon
So DP-2 port would be driving LSPCON device.

Now, your command line option video=DP-2:D has forced DP-2 on, which is LSPCON
Port too, which will bypass the natural DP detection path.
[    1.471722] [drm] forcing DP-2 connector on
[   19.208474] [drm:intel_dp_force] [CONNECTOR:69:DP-2]
[   19.208478] [drm:intel_power_well_enable] enabling always-on

Whereas drm.edid_firmware=DP-2:edid/edid.bin will ask driver to pick edid from
this hard-coded file, not from actual monitor. Now LSPCON's FW also reads EDID
from monitor, and uses it for Link training handling.

I think as Ville mentioned, your command line is messing up with LSPCON, So
remove this hard-coding of EDID, and it should fix this issue.

- Shashank

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the assignee for the bug.
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20180419/64c767d2/attachment.html>