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Date:   Fri, 1 Dec 2023 11:48:40 +0100
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To:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-i2c@vger.kernel.org
From:   Tor Vic <torvic9@mailbox.org>
Subject: [Bug Report] [6.6] i2c: No atomic i2c transfer handler
Cc:     benjamin.bara@skidata.com, dmitry.osipenko@collabora.com
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Hi,

Since Linux 6.6.3, I see some warnings in the late phase of shutdown.
Unfortunately, they are not logged because syslog has already shut down 
at that point.

I used a camera to capture a small part of the warnings:

   No atomic I2C transfer handler for 'i2c-0'
   [trace follows]
   i2c_smbus_xfer
   [...]

After checking the changelog, the culprit was found quickly:

   (3473cf43b) i2c: core: Run atomic i2c xfer when !preemptible

Reverting that commit made the warnings go away.

This is a voluntary preemption kernel running on a Skylake laptop.

Please tell me if you need more info.

Cheers,
Tor