[Pkg-raspi-maintainers] Bug#1010365: linux: failure to boot on Raspberry Pi Compute Module 4 (black screen)

[Cyril Brulebois]

Control: found -1 5.17~rc3-1~exp1

Cyril Brulebois <cyril at debamax.com> (2022-04-29):
> The usual start-up rainbow is displayed, the screen turns to black and
> nothing happens. My first stop was trying to downgrade the bootloader
> (shipped by the raspi-firmware package) to the bullseye's version, but
> that didn't help.
> 
> Then I moved to starting from a bullseye image (which boots), upgrading
> the raspi-firmware package, that still boots.
> 
> Then I deployed 5.16.18-1 (from snapshot.debian.org), that still boots.
> 
> Then I deployed 5.17.3-1, and it broke booting.
> 
> I'll try and pinpoint when it broke using the various intermediary
> versions:
> 
>  - 5.17~rc3-1~exp1

The first attempt was sufficient: it breaks as early as that version.

> and then try to figure out what broke exactly. Contrary to my earlier
> efforts to introduce support for that hardware a few months ago, I
> haven't been following upstream changes recently, so I'll need to catch
> up.

Checking the upstream diff, nothing obvious on the DTB side. Trying to
use 5.16.18-1's DTB with 5.17~rc3-1~exp1 kernel didn't help anyway.

I've also tried latest mainline: v5.18-rc4-192-g38d741cb70b3

built with:

    cp ~/config-5.17.0-1-arm64 .config
    time PATH=/usr/lib/ccache:$PATH make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- oldconfig       # accept everything
    time PATH=/usr/lib/ccache:$PATH make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg -j32

and the symptoms are the same: black screen at start-up.

I've also checked the serial console (which is confirmed to work if I
boot 5.16.18-1), and I'm not getting anything there either, with either
5.17~rc3-1~exp1 or my local v5.18-rc4-192-g38d741cb70b3 build.


Cheers,
-- 
Cyril Brulebois -- Debian Consultant @ DEBAMAX -- https://debamax.com/
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