Bug#1034438: i915: Flickering in framebuffer console and "*ERROR* CPU pipe A FIFO underrun" kernel message
Control: tags -1 + moreinfo
Hi Enrique,
On Sat, Apr 15, 2023 at 12:26:06PM +0200, Enrique Garcia wrote:
> Package: src:linux
> Version: 6.1.20-1
> Severity: normal
> X-Debbugs-Cc: cquike@arcor.de
>
> I have been running debian testing for a while and I see that from time to time
> a get a flickering screen when switching to the virtual console with Ctrl-
> Alt-F1. It does occur also ocassionally when booting the laptop just before
> systemctl starts printing the start messages.
> I can see the following messages with journalctl:
>
> abr 15 11:53:10 hostname kernel: i915 0000:00:02.0: [drm] *ERROR* CPU pipe A
> FIFO underrun
>
> There are other i915 related messages in the log, but it does not seem they are
> directly related to the problem:
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: [drm] VT-d active for gfx
> access
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: vgaarb: deactivate vga
> console
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: [drm] Using Transparent
> Hugepages
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: vgaarb: changed VGA
> decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: [drm] Disabling framebuffer
> compression (FBC) to prevent screen flicker with VT-d enabled
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: firmware: direct-loading
> firmware i915/skl_dmc_ver1_27.bin
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: [drm] Finished loading DMC
> firmware i915/skl_dmc_ver1_27.bin (v1.27)
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: [drm] [ENCODER:102:DDI
> B/PHY B] is disabled/in DSI mode with an ungated DDI clock, gate it
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: [drm] [ENCODER:117:DDI
> C/PHY C] is disabled/in DSI mode with an ungated DDI clock, gate it
> abr 15 11:41:46 hostname kernel: [drm] Initialized i915 1.6.0 20201103 for
> 0000:00:02.0 on minor 0
> abr 15 11:41:46 hostname kernel: fbcon: i915drmfb (fb0) is primary device
> abr 15 11:41:46 hostname kernel: i915 0000:00:02.0: [drm] fb0: i915drmfb frame
> buffer device
> abr 15 11:41:47 hostname kernel: snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0
> (ops i915_audio_component_bind_ops [i915])
> abr 15 11:52:49 hostname kernel: (NULL device *): firmware: direct-loading
> firmware i915/skl_dmc_ver1_27.bin
> abr 15 11:53:07 hostname kernel: i915 0000:00:02.0: [drm] [ENCODER:94:DDI A/PHY
> A] is disabled/in DSI mode with an ungated DDI clock, gate it
> abr 15 11:53:07 hostname kernel: i915 0000:00:02.0: [drm] [ENCODER:102:DDI
> B/PHY B] is disabled/in DSI mode with an ungated DDI clock, gate it
> abr 15 11:53:07 hostname kernel: i915 0000:00:02.0: [drm] [ENCODER:117:DDI
> C/PHY C] is disabled/in DSI mode with an ungated DDI clock, gate it
>
>
> Looking into the logs I can see that the problem started to appear when I
> upgraded my system to testing last August. The kernel that was installed was
> linux-image-5.18.0-3-amd64:amd64 (5.18.14-1, automatic) according to apt logs.
> Since then the kernel has been upgraded to the 6 series but the problem
> persists.
> The flickering happens every couple of seconds, which makes it inconvenient to
> work with the virtual console.
As you say you start noticing it with 5.18.14-1, would you be able to
verify it directly with 5.18.14, test as well 5.18.5 (which was the
basis for the previous update 5.18.5-1) and then bisect the changes
inbetween to determine the potential introducing commit?
And I assume you can still reproduce the issue with upstream's 6.1.24?
Regards,
Salvatore
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