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

[Cyril Brulebois]

Control: tag -1 upstream
Control: forwarded -1 https://bugzilla.kernel.org/show_bug.cgi?id=215925

Hi Bjørn,

Bjørn Mork <bjorn at mork.no> (2022-04-30):
> But that's a merge commit. Not likely the real cuplrit, unless there's
> a merge bug.
> 
> I looked briefly at what was merged there, and I believe this commit
> stands out as suspicious:
> 
> bjorn at miraculix:/usr/local/src/git/linux$ git show f59f6aaead97
> commit f59f6aaead975f0ec4d8ff2d59c4ffb8cf0127b2
> Author: Arnd Bergmann <arnd at arndb.de>
> Date:   Mon Nov 22 23:21:56 2021 +0100
> 
>     mmc: bcm2835: stop setting chan_config->slave_id

Yeah, I skipped a bunch of details in my last mail since I've tried
various things (including reverting that one I spotted, plus the few
commits around it since it was part of removing that field altogether)
but didn't get any consistent results.

My methodology was probably fragile since I worked incrementally, and I
suppose I got some wires crossed at some point. Sorry for the confusion.


I've redone this entirely, and here are better (and reproducible, this
time) findings:

 - 830aa6f29f07a4e2f1a947dfa72b3ccddb46dd21 breaks the boot, leading to
   a kernel panic very early in the boot process; I'm seeing the trace
   on the screen, not on the serial console. It involves the modified
   brcm_pcie_driver_init() function, so that's quite consistent.

 - 87c71931633bd15e9cfd51d4a4d9cd685e8cdb55 is the last commit
   exhibiting the kernel panic (further in that branch, before it gets
   merged into mainline).

 - 88db8458086b1dcf20b56682504bdb34d2bca0e2 is the last commit that lets
   the CM4 boots properly.

 - d0a231f01e5b25bacd23e6edc7c979a18a517b2b, which is the merge of the
   last two aforementioned commits, is the first one that results in
   a completely black screen (no kernel panic displayed), and still
   nothing on the serial console. It seems to me that the kernel panic
   escalates into a more serious issue after this merge. I note there
   are conflict resolutions about drivers/pci/controller/pcie-brcmstb.c
   in that commit.


No luck with latest master. I've filed this upstream (see link above).


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