[PATCH] i2c: exynos5: Properly use the "noirq" variants of suspend/resume
khilman at linaro.org
Mon Jun 23 15:19:11 PDT 2014
Doug Anderson <dianders at chromium.org> writes:
> On Fri, Jun 20, 2014 at 4:59 PM, Tomasz Figa <tomasz.figa at gmail.com> wrote:
>> I'm not sure noirq is going to work correctly, at least not with current
>> callbacks. I can see a call to clk_prepare_enable() there which needs to
>> acquire a mutex.
> Nice catch, thanks! :)
> OK, looking at that now. Interestingly this doesn't seem to cause us
> problems in our ChromeOS 3.8 tree. I just tried enabling:
> ...and confirmed that I got it on right:
> # zgrep -i atomic /proc/config.gz
> I can suspend/resume with no problems. My bet is that it works fine because:
> * resume_noirq is not considered "atomic" in the sense enforced by
> CONFIG_DEBUG_ATOMIC_SLEEP (at least not in 3.8--I haven't tried on
The reason is because "noirq" in the suspend/resume path actually means
no *device* IRQs for that specific device.
It's often assumed that the "noirq" callbacks are called with *all*
interrupts disabled, but that's not the case. Only the IRQs for that
specific device are disabled when its noirq callbacks run.
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