From mboxrd@z Thu Jan 1 00:00:00 1970 From: tomasz.figa@gmail.com (Tomasz Figa) Date: Tue, 24 Jun 2014 00:24:23 +0200 Subject: [PATCH] i2c: exynos5: Properly use the "noirq" variants of suspend/resume In-Reply-To: <7ha993p8v4.fsf@paris.lan> References: <1403155273-1057-1-git-send-email-dianders@chromium.org> <7h8uosyc3k.fsf@paris.lan> <7hwqcbs166.fsf@paris.lan> <7h7g4brx6w.fsf@paris.lan> <53A4CADA.4030002@gmail.com> <7ha993p8v4.fsf@paris.lan> Message-ID: <53A8A917.8090706@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 24.06.2014 00:19, Kevin Hilman wrote: > Doug Anderson writes: > > [...] > >> On Fri, Jun 20, 2014 at 4:59 PM, Tomasz Figa 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