Re: Commit 8ae030c34 breaks USB on the Raspberry Pi 4

Thanks for your mail.

My system does not use any Linux kernel modules (=m), all required
code is compiled into the kernel itself (=y).
The root file system does not contain any .ko files.


On Tue, 14 Sept 2021 at 23:47, Florian Fainelli [off-list ref] wrote:

+Nicolas, Stefan,

On 9/14/21 2:28 PM, Michael Stapelberg wrote:

quoted

[re-sending in plain text mode]

Hey!

Linux 5.14 broke USB on the Raspberry Pi 4 for me.

See https://github.com/gokrazy/kernel/commit/e06b78841ba4d2ce99a3f368cb8407951267e082
for more details regarding symptoms and a dmesg diff.

I used git-bisect to find the culprit, and it identified this commit:
https://github.com/torvalds/linux/commit/8ae030c34dce4f5764e945b325e8dc4d2adef044

Indeed, when I compare the kernel config before/with the commit, I see:

--- /tmp/config-WORKING 2021-09-14 23:04:03.180316634 +0200
+++ /tmp/config-BROKEN 2021-09-14 23:05:57.475549129 +0200

@@ -8101,7 +8101,7 @@
 CONFIG_RESET_MESON_AUDIO_ARB=m
 CONFIG_RESET_QCOM_AOSS=y
 CONFIG_RESET_QCOM_PDC=m
-CONFIG_RESET_RASPBERRYPI=y
+CONFIG_RESET_RASPBERRYPI=m
 CONFIG_RESET_SCMI=y
 CONFIG_RESET_SIMPLE=y
 CONFIG_RESET_SUNXI=y

So it seems like this innocuous-looking arm64 defconfig change has
accidentally (?) demoted CONFIG_RESET_RASPBERRYPI=y to
CONFIG_RESET_RASPBERRYPI=m in the arm64 defconfig.

Was this intentional? If not, I’d be happy if you could send a fix for
this change.

From a running system, can you see if reset-raspberry.ko is included in
your root filesystem? If not, this would definitively be an issue since
that driver is needed in order for xHCI to work on the Pi 4. There does
not appear to be any explicit dependency between reset-raspberry and
xhci-pci.ko, so without manually "front" loading the former before the
latter, I don't think we can have automatic dependencies.

quoted

Thank you!
Best regards
Michael

PS: I’m building the Linux kernel using this config addition to the
arm64 defconfig:
https://github.com/gokrazy/kernel/blob/master/cmd/gokr-build-kernel/build.go#L19,
just in case it matters…

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

--
Florian

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel