Bug 101012 - [ILK] Sporadic FIFO underruns
Summary: [ILK] Sporadic FIFO underruns
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: XOrg git
Hardware: Other All
: medium normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
Whiteboard: ReadyForDev
Depends on:
Blocks: 105980
  Show dependency treegraph
Reported: 2017-05-11 20:53 UTC by Clemens Eisserer
Modified: 2019-07-15 07:01 UTC (History)
3 users (show)

See Also:
i915 platform: ILK
i915 features: display/Other

syslog with drm.debug=0xe (29.69 KB, application/gzip)
2017-06-08 19:06 UTC, Clemens Eisserer
no flags Details
dmesg | grep drm (48.98 KB, text/plain)
2017-08-13 17:42 UTC, public
no flags Details

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Description Clemens Eisserer 2017-05-11 20:53:31 UTC
Running Fedora-25 (linux-4.10.14, Mesa-17.0.5, Glamor) on my Ironlake/Arrandale based Laptop, I get the following messages in syslog along with a flickering screen:

[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun
[drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder B FIFO underrun

Also, I have seen the system hang at least one time when it actually should modeswitch.
Comment 1 Clemens Eisserer 2017-05-13 07:52:29 UTC
when not using an external display, I only get a single overrun:

 [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
Comment 2 Clemens Eisserer 2017-05-23 19:33:09 UTC
This issue only seems to manifest when using modesetting+glamor, when using the intel-driver with SNA I don't get any of these.
Comment 3 Ville Syrjala 2017-06-07 20:08:58 UTC
Please add drm.debug=0xe to the kernel command line and attach the resulting dmesg.
Comment 4 Clemens Eisserer 2017-06-08 19:06:55 UTC
Created attachment 131815 [details]
syslog with drm.debug=0xe
Comment 5 Ville Syrjala 2017-06-20 20:02:28 UTC
Still 4.10 based kernel? The dmesg was cut off so I can't tell.

Can you try 4.12 or drm-tip? I'm thinking this may be have been fixed by

commit a5509abda48ecfc133fac6268e83fc1a93dba039
Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date:   Fri Feb 17 17:01:59 2017 +0200

    drm/i915: Fix legacy cursor vs. watermarks for ILK-BDW
Comment 6 Elizabeth 2017-08-03 19:40:41 UTC
(In reply to Clemens Eisserer from comment #4)
> Created attachment 131815 [details]
> syslog with drm.debug=0xe
Hello Clemens,
Any update on this case with the kernel suggested by Ville? Could you share please? 
Thank you.
Comment 7 Clemens Eisserer 2017-08-05 10:41:35 UTC
Hi Elisabeth,

I'll give 4.12 a try as soon as it will be rolled out for Fedora 25 (which should be any day now).
Comment 8 public 2017-08-12 18:02:37 UTC
I suspect I see the same bug on a Thinkpad T570, newest firmware 1.23..

The glitches are pretty rate, at most a few time a day if at all. Today I noticed [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun. I guess I haven't checked dmesg earlier.

On AC power and with a second display, the bug appears basically never. I think I observed it once but I cannot tell for sure whether it was on AC, second display or once. 

I'll try adding drm.debug=0xe.
Comment 9 public 2017-08-12 18:05:06 UTC
Forgot to mention that the bug appears significantly more often when using the integrated UMTS modem. I have no clue why this is related. Until now I suspected that the problem is related to power.
Comment 10 public 2017-08-13 17:42:06 UTC
Created attachment 133473 [details]
dmesg | grep drm

Log with drm.debug=0xe. 
This underrun happened without UMTS, on AC power but without an external monitor.
Comment 11 public 2017-08-13 17:43:31 UTC
This is on kernel 4.12.4.
Comment 12 Elizabeth 2017-08-14 15:27:54 UTC
Thanks for updating.
If more information is needed it will be requested in the comment section below. 
Also changing priority since it's a sporadic issue.
Comment 13 Clemens Eisserer 2017-08-25 14:57:04 UTC
Just experienced:

[ 1222.200551] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun
[ 1222.200626] [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder B FIFO underrun

on linux 4.12.8 with 2 monitors active (1x DisplayPort, 1x VGA, internal display disabled).
Comment 14 Jani Saarinen 2018-03-29 07:11:47 UTC
First of all. Sorry about spam.
This is mass update for our bugs. 

Sorry if you feel this annoying but with this trying to understand if bug still valid or not.
If bug investigation still in progress, please ignore this and I apologize!

If you think this is not anymore valid, please comment to the bug that can be closed.
If you haven't tested with our latest pre-upstream tree(drm-tip), can you do that also to see if issue is valid there still and if you cannot see issue there, please comment to the bug.
Comment 15 Martin Weinberg 2018-04-21 13:49:33 UTC
Yes, this continues to be a problem.  I tried both the drm-tip and the backported kernel in the Ubuntu 18.04 daily.   Both kernels still show the bug.
Comment 16 Jani Saarinen 2018-04-23 09:57:03 UTC
OK, thanks for confirming.
Comment 17 Lakshmi 2018-09-18 13:34:29 UTC
Reporter, do you still have the issue?
Please try to reproduce the issue using drm-tip (https://cgit.freedesktop.org/drm-tip) and kernel parameters drm.debug=0x1e log_buf_len=4M, and if the problem persists attach the full dmesg from boot.
Comment 18 Lakshmi 2018-10-21 18:07:23 UTC
Paulo, testing with latest drm-tip will help the situation?
Comment 19 Lakshmi 2018-10-25 06:43:17 UTC
Clemens, Do you still have the issue?
If so, can you attach dmesg from latest drm-tip for investigation. 
No feedback from few months, reducing the priority to medium.
Comment 20 public 2018-10-25 09:26:59 UTC
I still experience the issue with 4.18.16. I don't have the time to install the latest drm-tip but I'll try to provide a log at least. Unfortunately I don't see the bug very often.
Comment 21 Lakshmi 2019-07-15 07:01:03 UTC
No feedback from more than few months. Closing this issue WORKSFORME.
We need feedback from the drmtip. With no logs from drmtip it's not possible to investigate this issue further. 

Please reopen the issue if it occurs on drmtip.

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