From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Wed, 10 Apr 2013 21:59:09 +0200 Subject: [PATCH 05/18] cpuidle: make a single register function for all In-Reply-To: References: <1365603743-5618-1-git-send-email-daniel.lezcano@linaro.org> <1365603743-5618-6-git-send-email-daniel.lezcano@linaro.org> Message-ID: <5165C48D.5060303@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 04/10/2013 08:22 PM, Colin Cross wrote: > On Wed, Apr 10, 2013 at 7:22 AM, Daniel Lezcano > wrote: >> The usual scheme to initialize a cpuidle driver on a SMP is: >> >> cpuidle_register_driver(drv); >> for_each_possible_cpu(cpu) { >> device = &per_cpu(cpuidle_dev, cpu); >> cpuidle_register_device(device); >> } >> >> This code is duplicated in each cpuidle driver. >> >> On UP systems, it is done this way: >> >> cpuidle_register_driver(drv); >> device = &per_cpu(cpuidle_dev, cpu); >> cpuidle_register_device(device); >> >> On UP, the macro 'for_each_cpu' does one iteration: >> >> #define for_each_cpu(cpu, mask) \ >> for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) >> >> Hence, the initialization loop is the same for UP than SMP. >> >> Beside, we saw different bugs / mis-initialization / return code unchecked in >> the different drivers, the code is duplicated including bugs. After fixing all >> these ones, it appears the initialization pattern is the same for everyone. >> >> Let's add a wrapper function doing this initialization with a cpumask parameter >> for the coupled idle states and use it for all the drivers. > > Isn't this going to cause problems for big.LITTLE, which has two > independent sets of coupled cpus, and may even have different drivers > for the two types of cpu? AFAICT no, because the "low levels" API are still there, I mean cpuidle_register_driver and cpuidle_register_device. That will be up to the b.L driver to use the API which fits its need. -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog