Re: [Bug 215925] New: PCIe regression on Raspberry Pi Compute Module 4 (CM4) breaks booting

From: Cyril Brulebois <kibi@debian.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>,
	Jim Quinlan <jim2101024@gmail.com>,
	"regressions@lists.linux.dev" <regressions@lists.linux.dev>,
	Linux PCI <linux-pci@vger.kernel.org>,
	bjorn@helgaas.com
Subject: Re: [Bug 215925] New: PCIe regression on Raspberry Pi Compute Module 4 (CM4) breaks booting
Date: Tue, 10 May 2022 22:07:09 +0200	[thread overview]
Message-ID: <20220510200709.vudemjipdvm2tpkq@mraw.org> (raw)
In-Reply-To: <20220510172243.GA684299@bhelgaas>

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Bjorn Helgaas <helgaas@kernel.org> (2022-05-10):
> What if you revert 830aa6f29f07 and the subsequent brcmstb patches?
> 
>   11ed8b8624b8 ("PCI: brcmstb: Do not turn off WOL regulators on suspend")
>   93e41f3fca3d ("PCI: brcmstb: Add control of subdevice voltage regulators")
>   67211aadcb4b ("PCI: brcmstb: Add mechanism to turn on subdev regulators")
>   830aa6f29f07 ("PCI: brcmstb: Split brcm_pcie_setup() into two funcs")
> 
>   $ git revert 11ed8b8624b8 93e41f3fca3d 67211aadcb4b 830aa6f29f07
> 
> I did that on current upstream: 9be9ed2612b5 ("Merge tag
> 'platform-drivers-x86-v5.18-4' of
> git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86")
> and it built fine on x86.

I've done exactly that, and it boots again. Comparing kernel messages
against an older version (5.10.106), I'm getting the same output on that
bare CM4 on CM4 IO Board setup:

    # dmesg|grep -i pcie
    [    3.368620] brcm-pcie fd500000.pcie: host bridge /scb/pcie@7d500000 ranges:
    [    3.368654] brcm-pcie fd500000.pcie:   No bus range found for /scb/pcie@7d500000, using [bus 00-ff]
    [    3.368703] brcm-pcie fd500000.pcie:      MEM 0x0600000000..0x0603ffffff -> 0x00f8000000
    [    3.368748] brcm-pcie fd500000.pcie:   IB MEM 0x0000000000..0x003fffffff -> 0x0400000000
    [    3.421094] brcm-pcie fd500000.pcie: link up, 5.0 GT/s PCIe x1 (SSC)
    [    3.421341] brcm-pcie fd500000.pcie: PCI host bridge to bus 0000:00

And with a PCIe → quad-USB board plugged in, I'm getting those
additional lines:

    [    3.426842] pcieport 0000:00:00.0: enabling device (0000 -> 0002)
    [    3.427072] pcieport 0000:00:00.0: PME: Signaling with IRQ 51
    [    3.427472] pcieport 0000:00:00.0: AER: enabled with IRQ 51

(It seems to be consistently IRQ 51 with 5.18.0-rc6+ while it seems to
be consistently IRQ 52 on 5.10.106, but the output is very similar in
both cases.)

And plugging a keyboard on one of those USB ports works fine:

    [   13.406351] input: Logitech USB Keyboard as /devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb1/1-1/1-1.2/1-1.2:1.0/0003:046D:C31C.0001/input/input0
    [   13.510144] input: Logitech USB Keyboard Consumer Control as /devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb1/1-1/1-1.2/1-1.2:1.1/0003:046D:C31C.0002/input/input2
    [   13.591345] input: Logitech USB Keyboard System Control as /devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb1/1-1/1-1.2/1-1.2:1.1/0003:046D:C31C.0002/input/input3

Wrapping up: it boots again (with or without PCIe equipment plugged in),
and PCIe seems functional.

I'm happy to test more patches (e.g. trying to fix the actual issue
without going for a set of reverts).

Cheers,
-- 
Cyril Brulebois (kibi@debian.org)            <https://debamax.com/>
D-I release manager -- Release team member -- Freelance Consultant

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