#964734 linux-image-4.19.0-9-amd64: [bisected] i2c timeout loading module ddbridge

Package:
src:linux
Source:
linux
Submitter:
Bernhard Turmann
Date:
2021-10-18 14:45:03 UTC
Severity:
normal
Tags:
#964734#5
Date:
2020-07-09 16:26:26 UTC
From:
To:
Dear Maintainer,
loading kernel module ddbridge fails with i2c timeouts. The dvb media
adapter is unusable.
This happened after Linux kernel upgrade from 4.19.98-1+deb10u1 to
4.19.118-2+deb10u1.

Git bisect based on the Debian kernel repo on branch buster identified
as first bad commit: [1fb0eb795661ab9e697c3a053b35aa4dc3b81165] Update
to 4.19.116.
Git bisect based on upstream Linux kernel repo on branch v4.19.y
identified as first bad commit:
[d2345d1231d80ecbea5fb764eb43123440861462] PCI: Add boot interrupt quirk
mechanism for Xeon chipsets.

Other affected Debian kernel version: 5.6.14+2~bpo10+1
I tested this version via buster-backports, because so far I was unable
to build my own kernel from 5.6.y or even 5.7.y.

Following kernel from buster backports is working OK:
linux-image-5.5.0-0.bpo.2-amd64 (5.5.17-1~bpo10+1)

Workaround:
==========
Reverting the mentioned commit d2345d1231d80ecbea5fb764eb43123440861462
on top of 4.19.132 is fixing the problem. Reverting the same commit on
4.19.118 or 4.19.116 is also fixing the problem.

I already reported upstream:
https://bugzilla.kernel.org/show_bug.cgi?id=208507

Thanks and Regards
Berni
#964734#10
Date:
2020-07-09 17:06:14 UTC
From:
To:
Attached is a patch to revert the mentioned commit
It is based on kernel v4.19.131.
#964734#17
Date:
2020-07-10 08:43:12 UTC
From:
To:
FTR, the problem stays the same also with newer upstream kernel
versions, tested:

- 5.8.0-rc4
- 5.7.8

It always works with reverted commit b88bf6c3b6ff ("PCI: Add boot
interrupt quirk mechanism for Xeon chipsets")

See more details in the upstream bug report.

Regards
Berni
#964734#24
Date:
2020-09-10 15:56:15 UTC
From:
To:
After enabling MSI within /etc/modprobe.d/ the card is working as expected:

 options ddbridge msi=1

Upstream bug report has been updated accordingly.

Regards
Berni
#964734#29
Date:
2020-09-10 16:17:12 UTC
From:
To:
Close, because workaround exist.
#964734#38
Date:
2020-09-11 07:18:53 UTC
From:
To:
Reopened until the resolution is clarified upstream.
#964734#45
Date:
2021-05-02 13:00:19 UTC
From:
To:
Hi Bernhard,

Was there some further progress/clarification from upstream?

Regards,
Salvatore
#964734#52
Date:
2021-05-03 17:11:09 UTC
From:
To:
Hallo Salvatore,

Am 02.05.21 um 15:00 schrieb Salvatore Bonaccorso:
I just tested with 5.12.0-11146-g8ca5297e7e3 to no avail and reported
the result upstream / asked for any update, if available.
Other than that, I am not much of any help here, I am afraid.

Regards
Berni
#964734#59
Date:
2021-10-17 12:56:37 UTC
From:
To:
Hi Bernhard,

Is this issue still present with a recent kernel from unstable or
bullseye-backports?

Regards,
Salvatore
#964734#64
Date:
2021-10-18 14:42:01 UTC
From:
To:
Hello Salvatore,

Am 17.10.21 um 14:56 schrieb Salvatore Bonaccorso:

Yes, unfortunately, I just tested with 5.14.9-2~bpo11+1 and can confirm
the same issue.
(using "options ddbridge msi=1" still works as a workaround)

With Regards
Berni