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Date:   Thu, 27 Jan 2022 23:24:03 +0000
From:   Sudip Mukherjee <sudipm.mukherjee@gmail.com>
To:     Wander Lairson Costa <wander@redhat.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Jiri Slaby <jirislaby@kernel.org>,
        linux-serial@vger.kernel.org
Subject: Regression with 5021d709b31b ("tty: serial: Use fifo in 8250 console
 driver")
Message-ID: <YfMpk7DM9zA7NfmI@debian>
MIME-Version: 1.0
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Hi Wander,

Not sure if this has been reported before but since last few weeks I am
seeing a problem with the rpi4 serial port on my test setup. The initial
boot message will be completely garbled as you can see at:
https://lava.qa.codethink.co.uk/scheduler/job/543#L380.
The last good boot was https://lava.qa.codethink.co.uk/scheduler/job/540#L390.

The bisect log:

# bad: [455e73a07f6e288b0061dfcf4fcf54fa9fe06458] Merge tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux
# good: [7e7b69654724c72bd3219b71f58937845dca0b2b] Merge tag 'dma-mapping-5.17' of git://git.infradead.org/users/hch/dma-mapping
git bisect start '455e73a07f6e288b0061dfcf4fcf54fa9fe06458' '7e7b69654724c72bd3219b71f58937845dca0b2b'
# bad: [342465f5337f7bd5b8bd3b6f939ac12b620cbb43] Merge tag 'tty-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
git bisect bad 342465f5337f7bd5b8bd3b6f939ac12b620cbb43
# good: [6dc69d3d0d18d587ab9d809fe060ba4417cf0279] Merge tag 'driver-core-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
git bisect good 6dc69d3d0d18d587ab9d809fe060ba4417cf0279
# good: [e269f7acdc53623769da31135f60afeb3a65eaff] staging: r8188eu: remove the private ioctl "wps_assoc_req_ie"
git bisect good e269f7acdc53623769da31135f60afeb3a65eaff
# bad: [ad234e2bac274a43c9fa540bde8cd9f0c627b71f] tty: serial: meson: Drop the legacy compatible strings and clock code
git bisect bad ad234e2bac274a43c9fa540bde8cd9f0c627b71f
# good: [c66453ce8af8bac78a72ba4e21fd9a86720127d7] tty: fix kernel-doc in n_tty.c
git bisect good c66453ce8af8bac78a72ba4e21fd9a86720127d7
# good: [0882b473b084df31288003b3bee974aabac9dcf9] tty: serial: samsung: Enable console as module
git bisect good 0882b473b084df31288003b3bee974aabac9dcf9
# bad: [b4a29b94804c4774f22555651296b838df6ec0e4] serial: 8250: Move Alpha-specific quirk out of the core
git bisect bad b4a29b94804c4774f22555651296b838df6ec0e4
# good: [e822b4973f49015e1c6f63b91c8641ed9bfaf229] tty/ldsem: Fix syntax errors in comments
git bisect good e822b4973f49015e1c6f63b91c8641ed9bfaf229
# good: [fb09d0ac07725b442b32dbf53f0ab0bea54804e9] tty: Fix the keyboard led light display problem
git bisect good fb09d0ac07725b442b32dbf53f0ab0bea54804e9
# bad: [5021d709b31b8a14317998a33cbc78be0de9ab30] tty: serial: Use fifo in 8250 console driver
git bisect bad 5021d709b31b8a14317998a33cbc78be0de9ab30
# good: [adbfddc757aec1ed54ccb35c4a7ca9170df827e0] docs/driver-api: Replace a comma in the n_gsm.rst with a double colon
git bisect good adbfddc757aec1ed54ccb35c4a7ca9170df827e0
# first bad commit: [5021d709b31b8a14317998a33cbc78be0de9ab30] tty: serial: Use fifo in 8250 console driver

And, indeed reverting 5021d709b31b ("tty: serial: Use fifo in 8250 console
driver") on top of 23a46422c561 ("Merge tag 'net-5.17-rc2' of
git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net") fixes the problem
for me.

This is seen on every boot and I will be happy to test any patch.


--
Regards
Sudip