On Sat, Apr 30, 2022 at 2:53 PM <bugzilla-daemon@xxxxxxxxxx> wrote: > > https://bugzilla.kernel.org/show_bug.cgi?id=215925 > > Bug ID: 215925 > Summary: PCIe regression on Raspberry Pi Compute Module 4 (CM4) > breaks booting > Product: Drivers > Version: 2.5 > Kernel Version: v5.17-rc1 > Hardware: ARM > OS: Linux > Tree: Mainline > Status: NEW > Severity: normal > Priority: P1 > Component: PCI > Assignee: drivers_pci@xxxxxxxxxxxxxxxxxxxx > Reporter: kibi@xxxxxxxxxx > Regression: No > > Catching up with latest kernel releases in Debian, it turned out that my > Raspberry Pi Compute Module 4, mounted on an official Compute Module 4 IO > Board, > and booting from an SD card, no longer boots: this means a black screen on the > HDMI output, and no output on the serial console. > > Trying various releases, I confirmed that v5.16 was fine, and v5.17-rc1 was the > first (pre)release that wasn't. > > After some git bisect, it turns out the cause seems to be the following commit > (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=830aa6f29f07a4e2f1a947dfa72b3ccddb46dd21): > > ``` > commit 830aa6f29f07a4e2f1a947dfa72b3ccddb46dd21 > Author: Jim Quinlan <jim2101024@xxxxxxxxx> > Date: Thu Jan 6 11:03:27 2022 -0500 > > PCI: brcmstb: Split brcm_pcie_setup() into two funcs > ``` > > Starting with this commit, the kernel panics early (before 0.30 seconds), with > an `Asynchronous SError Interrupt`. The backtrace references various > `brcm_pcie_*` functions; I can share a picture or try and transcribe it > manually if that helps (nothing on the serial console…). > > This commit is part of a branch that was ultimately merged as > d0a231f01e5b25bacd23e6edc7c979a18a517b2b; starting with this commit, there's > not even a backtrace anymore, the screen stays black after the usual “boot-up > rainbow”, and there's still nothing on the serial console. > > I confirmed that 88db8458086b1dcf20b56682504bdb34d2bca0e2 (on the master side) > was still booting properly, and that 87c71931633bd15e9cfd51d4a4d9cd685e8cdb55 > (from the branch being merged into master) is the last commit showing the > panic. > > Since d0a231f01e5b25bacd23e6edc7c979a18a517b2b is a merge commit that includes > conflict resolutions in drivers/pci/controller/pcie-brcmstb.c, I suppose this > could be consistent with the initial panic being “upgraded” into an even more > serious issue. > > I've also verified that latest master (v5.18-rc4-396-g57ae8a492116) is still > affected by this issue. > > The regular Raspberry Pi 4 B doesn't seem to be affected by this issue: the > exact same image on the same SD card (with latest master) boots fine on it.
