Bug 217328 - Open Firmware framebuffer cannot find of-display
Summary: Open Firmware framebuffer cannot find of-display
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: Console/Framebuffers (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: James Simmons
URL: https://bugs.debian.org/1033058
Keywords:
Depends on:
Blocks:
 
Reported: 2023-04-12 09:02 UTC by Cyril Brulebois
Modified: 2023-04-12 11:14 UTC (History)
1 user (show)

See Also:
Kernel Version: v6.2-rc8
Subsystem:
Regression: Yes
Bisected commit-id: 241d2fb56a18473af5f2ff0d512992a996eb64dd


Attachments

Description Cyril Brulebois 2023-04-12 09:02:45 UTC
Hi,

Initially spotted in Debian as a regression of the Debian Installer on ppc64el, which is currently following the stable linux-6.1.y branch: v6.1.12 regresses, and the installer gets stuck on a black screen instead of opening the usual interface.

Frédéric Bonnard checked that reverting 241d2fb56a18473af5f2ff0d512992a996eb64dd (first shipped in v6.2-rc8) makes the regression go away. For completeness, the regression shows up in the linux-6.1.y branch via the a7f0ec26cd67e7ad6e56753694fddb67a9730f27 cherry-pick (first shipped in v6.1.12).

Since the existing code in drivers/video/fbdev/offb.c only cares about "of-display", I've tested switching it to caring about "of-display.0" instead (without looping/trying possible other device nodes), and the resulting Debian Installer builds starts happily again.

I'll submit the patch in a moment, I wanted to have a reference in bugzilla first.

I've noticed that drivers/gpu/drm/tiny/ofdrm.c (first shipped in v6.2-rc1) is very likely to have the exact same problem, but I don't think I can easily confirm this. I might submit a patch for it anyway.
Comment 1 Cyril Brulebois 2023-04-12 10:01:46 UTC
The cover letter and the two patches: https://lore.kernel.org/all/20230412095509.2196162-1-cyril@debamax.com/T/#t

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