Messages in this thread | | | Date | Tue, 24 Jun 2014 00:24:23 +0200 | From | Tomasz Figa <> | Subject | Re: [PATCH] i2c: exynos5: Properly use the "noirq" variants of suspend/resume |
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On 24.06.2014 00:19, Kevin Hilman wrote: > Doug Anderson <dianders@chromium.org> writes: > > [...] > >> On Fri, Jun 20, 2014 at 4:59 PM, Tomasz Figa <tomasz.figa@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: >> CONFIG_DEBUG_ATOMIC_SLEEP=y >> >> ...and confirmed that I got it on right: >> >> # zgrep -i atomic /proc/config.gz >> CONFIG_DEBUG_ATOMIC_SLEEP=y >> >> 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 >> ToT) > > 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.
Thanks for clarifying this. This means that we should be fine with the noirq variant then.
Best regards, Tomasz
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