Arch Linux

TimonP

Member

Registered: 2020-01-20

Posts: 12

[SOLVED] cpu pipe a fifo underrun

I get this error message in journalctl sometimes:

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

I think this is related to the flickering I see sometimes in a small horizontal bar when scrolling. The height of the bar changes sometimes when I stop scrolling and start again. The bar is only inside the window I'm scrolling in.

I looked at many, many forum posts about this error message and no fix works, so I'm kind of clueless.

This is /etc/X11/xorg.conf.d/20-intel.conf:

Section "Device"
    Identifier "Intel Graphics"
    Driver "intel"
    # This is one fix that doesn't work.
    Option "AccelMethod" "uxa"
    # This is another.
    Option "TearFree" "true"
EndSection

Last edited by TimonP (2020-03-20 10:20:06)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,707

Re: [SOLVED] cpu pipe a fifo underrun

Remove that file, and xf86-video-intel with it. I haven't yet seen this log message (and FWIW many xf86-video-intel issues) surface on the modesetting driver. However you might want to set up a proper compositor to be extra sure.

Also in any case uxa and TearFree true are incompatible with each other.

TimonP

Member

Registered: 2020-01-20

Posts: 12

Re: [SOLVED] cpu pipe a fifo underrun

and xf86-video-intel with it

I should remove the whole driver? Doesn't that make rendering much much slower?

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,707

Re: [SOLVED] cpu pipe a fifo underrun

No, xorg will fall back to the modesetting driver, which uses glamor and OpenGL to provide xorg acceleration.

It might be slightly slower for things that do large amounts of 2D xorg operations, but that is not the case for the majority of modern software. It is also in much more active development than xf86-video-intel and generally recommended on newer intel chips.

TimonP

Member

Registered: 2020-01-20

Posts: 12

Re: [SOLVED] cpu pipe a fifo underrun

I did what you said and the bug looks different now because there are multiple lines and some move up and down in a weird dampened way. So it's worse now.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,707

Re: [SOLVED] cpu pipe a fifo underrun

What system and GPU is this exactly? As mentioned to really properly fix standard tearing you will often want to set up a dedicated compositor. You might also want to try and disable psr: https://wiki.archlinux.org/index.php/In … flickering

TimonP

Member

Registered: 2020-01-20

Posts: 12

Re: [SOLVED] cpu pipe a fifo underrun

The graphics card is an Intel on board GPU, device 5906, revision 2.

lspci output:

00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 02)
00:02.0 VGA compatible controller: Intel Corporation Device 5906 (rev 02)
00:04.0 Signal processing controller: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem (rev 02)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point LPC Controller (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
01:00.0 Network controller: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31)

TimonP

Member

Registered: 2020-01-20

Posts: 12

Re: [SOLVED] cpu pipe a fifo underrun

I set the kernel parameter and the flickering is acceptable now, thank you. (-:

TimonP

Member

Registered: 2020-01-20

Posts: 12

Re: [SOLVED] cpu pipe a fifo underrun

By the way, even though psr is supposed to save power, in my case disabling it doesn't increase power consumption in any noticeable way.

Last edited by TimonP (2020-03-20 10:31:28)

kuvaldini

Member

Registered: 2022-02-01

Posts: 1

Re: [SOLVED] cpu pipe a fifo underrun

I have also set the kernel parameter and the flickering disappeared, thank you. (-:

2ManyDogs

Forum Fellow

Registered: 2012-01-15

Posts: 4,645

Re: [SOLVED] cpu pipe a fifo underrun

Closing this old solved topic.