Bug 1090467

Summary: *ERROR* CPU pipe A FIFO underrun (on Intel N3450)
Product: [openSUSE] openSUSE Tumbleweed Reporter: Alex Sinev <quicktrick>
Component: KernelAssignee: E-mail List <kernel-maintainers>
Status: RESOLVED UPSTREAM QA Contact: E-mail List <qa-bugs>
Severity: Normal    
Priority: P5 - None CC: jslaby, quicktrick, tiwai
Version: CurrentFlags: tiwai: needinfo? (quicktrick)
Target Milestone: ---   
Hardware: x86-64   
OS: openSUSE Factory   
Whiteboard:
Found By: --- Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---
Attachments: dmesg output
dmesg output with debug

Description Alex Sinev 2018-04-22 06:45:04 UTC
Created attachment 767908 [details]
dmesg output

Intel Celeron Processor N3450
https://ark.intel.com/products/95596/Intel-Celeron-Processor-N3450-2M-Cache-up-to-2_2-GHz

In a few minutes after the boot there appears the following error in the dmesg output:

[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

This issue first appeared, I think, on kernel 4.15.
Comment 1 Alex Sinev 2018-04-22 06:47:48 UTC
Intel Celeron Processor N3450
https://ark.intel.com/products/95596/Intel-Celeron-Processor-N3450-2M-Cache-up-to-2_2-GHz

In a few minutes after the boot there appears the following error in the dmesg output:

[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

This issue first appeared, I think, on kernel 4.15.
Comment 2 Takashi Iwai 2018-04-22 07:14:25 UTC
Do you see any real issue other than the error message?

The FIFO underrun can be seen in some unexpected situation in GPU, but often it's not so harmful, and appears sometimes on old Intel chips (e.g. something was tried while the laptop display is off).

In anyway, if you know how to reproduce this reliably, try to enable the drm debug beforehand:
  echo 0x0e > /sys/module/drm/parameters/debug
and trigger the bug.  Then upload the dmesg output.  This might be help for debugging by upstream dev.
Comment 3 Alex Sinev 2018-04-22 07:37:38 UTC
Created attachment 767909 [details]
dmesg output with debug
Comment 4 Alex Sinev 2018-04-22 07:39:13 UTC
I use this computer in a server text mode only, so I don't see any issue other than the error message.
Comment 5 Takashi Iwai 2018-04-30 12:18:08 UTC
(In reply to Alex Sinev from comment #3)
> Created attachment 767909 [details]
> dmesg output with debug

Unfortunately it was too late, the driver was already loaded and the bug was triggered.  You can pass drm.debug=0x0e boot option instead to set it from the beginning.

In anyway, at best, please report it to the upstream bugzilla, bugzilla.freedesktop.org.  Use the category DRI/Intel.
Feel free to put me (tiwai@suse.de) to Cc in case you need help for packaging.
Comment 6 Jiri Slaby 2018-06-16 12:31:12 UTC
.