Re: [PATCH] i2c: core: Fix atomic xfer check for non-preempt config

[Askar Safin <safinaskar@zohomail.com>]

Thanks a lot for this patch! It fixed big backtrace I saw at very last stage of reboot. That
backtrace occupied whole FullHD screen. Now it is gone. Thanks! My computer is laptop Dell Inspiron.

I hope this patch will soon arrive to debian buster lts

Askar Safin

> Since commit aa49c90894d0 ("i2c: core: Run atomic i2c xfer when
> !preemptible"), the whole reboot/power off sequence on non-preempt kernels
> is using atomic i2c xfer, as !preemptible() always results to 1.

> During device_shutdown(), the i2c might be used a lot and not all busses
> have implemented an atomic xfer handler. This results in a lot of
> avoidable noise, like:

> [   12.687169] No atomic I2C transfer handler for 'i2c-0'
> [   12.692313] WARNING: CPU: 6 PID: 275 at drivers/i2c/i2c-core.h:40 i2c_smbus_xfer+0x100/0x118
> ...

> Fix this by allowing non-atomic xfer when the interrupts are enabled, as
> it was before.

> Fixes: aa49c90894d0 ("i2c: core: Run atomic i2c xfer when !preemptible")
> Cc: stable@vger.kernel.org # v5.2+
> Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>