Bug 1182349 - WARNING: CPU: 7 PID: 90 at ../drivers/gpu/drm/i915/display/intel_dp.c:1895 intel_dp_max_link_rate+0x7e/0xa0
WARNING: CPU: 7 PID: 90 at ../drivers/gpu/drm/i915/display/intel_dp.c:1895 in...
Status: NEW
Classification: openSUSE
Product: openSUSE Distribution
Classification: openSUSE
Component: Kernel
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: P5 - None : Normal (vote)
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Assigned To: openSUSE Kernel Bugs
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Reported: 2021-02-17 07:54 UTC by Hannes Reinecke
Modified: 2022-02-18 09:44 UTC (History)
4 users (show)

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dmesg.log (1.02 MB, text/x-log)
2021-02-17 07:56 UTC, Hannes Reinecke
U2417H.bin (256 bytes, application/octet-stream)
2021-02-17 07:56 UTC, Hannes Reinecke

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Description Hannes Reinecke 2021-02-17 07:54:06 UTC
Trying to feed an external EDID for i915 to facilitate headless operation on an Intel NUC resulted in repeated warnings

Feb 17 08:47:38 localhost kernel: ------------[ cut here ]------------
Feb 17 08:47:38 localhost kernel: i915 0000:00:02.0: drm_WARN_ON(len <= 0)
Feb 17 08:47:38 localhost kernel: WARNING: CPU: 7 PID: 90 at ../drivers/gpu/drm/i915/display/in>

and a non-working display.
(Arguably the display doesn't work as it's headless, but the vncviewer for Intel AMT stays blank, too. It doesn't when a monitor is connected.)
Comment 1 Hannes Reinecke 2021-02-17 07:56:15 UTC
Created attachment 846192 [details]

Dmesg log
Comment 2 Hannes Reinecke 2021-02-17 07:56:58 UTC
Created attachment 846193 [details]

EDID data.
Comment 3 Takashi Iwai 2021-02-17 09:00:37 UTC
AFAIK, the WARN_ON() has been always present in that function.
Didn't this appear in the earlier kernels?
Comment 4 Takashi Iwai 2021-02-17 13:18:49 UTC
Anyway, the obvious "fix" should be just to drop WARN_ON().  It makes no sense to trigger a kernel WARNING with stack trace for the data that can be provided externally.  It could be at most a debug message.
Comment 5 Miroslav Beneš 2022-02-18 09:44:34 UTC
Has anything happened here? Has it been brought up in upstream?