[Bug 103400] New: [KBL] Black screen at boot, unknown DP link BW code 0 warning

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=103400

            Bug ID: 103400
           Summary: [KBL] Black screen at boot, unknown DP link BW code 0
                    warning
           Product: DRI
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: issun.artiste at gmail.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org
     i915 platform: KBL
     i915 features: display/eDP

Created attachment 134984
  --> https://bugs.freedesktop.org/attachment.cgi?id=134984&action=edit
dmesg from drm-tip with drm.debug=0x1e (commit:
9dd506b9e3b79799503694e9c1bb5aba0d7d72eb)

Hello,

Kernel version: At least since 4.9 (previous versions unteseted), up
                until latest drm-tip
Linux distribution: Archlinux
Machine model: MSI GE63VF 7RF (Intel i7 7700HQ with HD Graphics 630)
Display connector: eDP

Description:
While booting, my laptop's screen turns black (with backlights on) when
the i915 module is loaded. The virtual console doesn't show up and Xorg
wont start. The only way to get my virtual console displayed is by
passing nomodeset as kernel parameter. I've observed this issue on
kernel version 4.9, 4.13, 4.14-rc5 and finally on the current head of
drm-tip. The following warning can be noticed with the latest drm-tip:

> [   16.096671] unknown DP link BW code 0, using 162000
> [   16.096685] ------------[ cut here ]------------
> [   16.096688] WARNING: CPU: 0 PID: 316 at drivers/gpu/drm/drm_dp_helper.c:157 drm_dp_bw_code_to_link_rate+0x3b/0x50 [drm_kms_helper]

Since it's a bit long, I didn't paste the entire warning, it can be found
in the enclosed dmesg.
I noticed that the warning location changed between the kernel mainline
and the drm-tip branch, but it seems to refer to the same problem. Here
are the first line of the warning on the kernel mainline (if it's
required, I could provide this dmesg too):

> invalid max DP link bw val 0, using 1.62Gbps
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 318 at drivers/gpu/drm/i915/intel_dp.c:144 intel_dp_num_rates+0x3b/0x50 [i915]

Also, this only affects my laptop's screen, I can use an external
display since it goes through my Nvidia card.

If you need any further information, please just ask.
Best regards,

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