Re: [BUG] exynos5_i2c_xfer_atomic() can sleep.

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 08.05.2026 12:42, Sebastian Andrzej Siewior wrote:
> On 2026-05-08 12:35:51 [+0200], Marek Szyprowski wrote:
>> Ah, it looks that I've checked irq_disable() code, so that's why I
>> didn't find might_sleep() call. In the case of exynos5_i2c driver,
>> probably switching to disable_irq_nosync() will be enough. I assume
>> that all previous transfers have to be finished to start this atomic
>> one, so waiting for interrupts to finish is not needed.
> This looks kind of odd. Are the "other" transfers really done at this
> point? Do you have a backtrace for me from the atomic path?

I thought that i2c core somehow serializes the transfers for the given master.

> Is this needed because you need to send the "power off" command via i2c?

Yes, most embedded boards do power off by sending i2c command to PMIC chip.


> Could you try to test with PREEMPT_RT? I'm sure how this works there.

I will check this, but so far I run all my tests without PREEMPT_RT

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland