From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Thu, 15 Jan 2015 13:23:24 +0100 Subject: [PATCH] clocksource: timer-atmel-pit: don't suspend/resume if unused In-Reply-To: <20150115115209.GS3843@piout.net> References: <1418911523-28492-1-git-send-email-nicolas.ferre@atmel.com> <54B3D450.7050405@atmel.com> <54B3D88C.80702@linaro.org> <54B7A767.9000205@linaro.org> <20150115115209.GS3843@piout.net> Message-ID: <54B7B13C.3090803@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/15/2015 12:52 PM, Alexandre Belloni wrote: > Hi, > > I'll do it but only if you review my other series :) deal ! ;) -- Daniel > > On 15/01/2015 at 12:41:27 +0100, Daniel Lezcano wrote : >> On 01/13/2015 11:47 AM, Thomas Gleixner wrote: >>> On Mon, 12 Jan 2015, Daniel Lezcano wrote: >>> >>>> On 01/12/2015 03:04 PM, Nicolas Ferre wrote: >>>>> Le 18/12/2014 15:05, Nicolas Ferre a ?crit : >>>>>> From: Sylvain Rochet >>>>>> >>>>>> Waiting for PIT to stop counting takes a long time: >>>>>> 1/(Master clock/prescaler/PIVR) >>>>>> = 1/(133 MHz /16 /2^20) >>>>>> = 126 ms >>>>>> >>>>>> Up to 126 ms if master clock is set to 133 MHz, skipping suspend/resume >>>>>> of the unused PIT device reduce (suspend time + resume time) from ~140 ms >>>>>> to ~17 ms. >>>>>> >>>>>> Signed-off-by: Sylvain Rochet >>>>>> [nicolas.ferre at atmel.com: move to newer clocksource driver] >>>>>> Signed-off-by: Nicolas Ferre >>>>>> Cc: Daniel Lezcano >>>>>> --- >>>>>> Hi Sylvain, >>>>>> >>>>>> I re-worked (and "Acked") your patch so it can be applied on the newer >>>>>> Mainline >>>>>> kernels. Beware, I changed the "subject line" as well. The PIT driver >>>>>> moved >>>>>> recently (3.18). >>>>>> >>>>>> Daniel, >>>>>> Can you take this patch in your tree? >>>>> >>>>> Hi Daniel, >>>>> >>>>> Anything prevents this patch from being merged (aka ping ;-))? >>>> >>>> [Cc'ed tglx]. >>>> >>>> Hi Nico, >>>> >>>> thanks for the head up. >>>> >>>> Nothing prevents it but I am wondering if this change shouldn't be in the >>>> generic framework (kernel/time/clocksource.c and kernel/time/clockevents.c), >>>> so all drivers will benefit this change ? >>> >>> Indeed. There is no point in calling suspend/resume for unused >>> clockevents. They should be stopped and disabled already. >> >> Hi Nico, >> >> are you planning to do the change in the generic framework ? >> >> Thanks >> -- Daniel >> >>> Now with clocksources this might be different. We have no explicit >>> state for this, but its trivial to add one at least for those >>> clocksources which have enable/disable callbacks. For the other ones >>> not so much. >> >> >> >> >> >> -- >> Linaro.org ? Open source software for ARM SoCs >> >> Follow Linaro: Facebook | >> Twitter | >> Blog >> > -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog