On 29 May 2013 03:18, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > On Tuesday, May 28, 2013 03:26:25 PM Lukasz Majewski wrote: >> Hi Viresh, Rafael, >> >> > On Tuesday, May 28, 2013 03:14:26 PM Viresh Kumar wrote: >> > I'm not sure about that. On x86 boost will be used with all >> > governors if enabled (as currently defined in acpi-cpufreq). >> >> All governors can benefit from the overclocking code. Yeah. >> > Also it looks like this depends on the driver too, because if the >> > driver doesn't have "turbo" frequencies, the governor won't be able >> > use "turbo" anyway. Yes. >> > So first, it would make sense to use a per-driver "boost" attribute >> > indicating whether or not the given driver should present any "turbo" >> > frequencies to the governor. @Lukasz: So, you need to add another field in struct cpufreq_driver, which will be called "turbo_mode" or something better. >> Now I'm using a device tree's cpufreq section (defined at >> exynos4412-redwood.dts) with overclocking = "okay" attribute defined. >> Then, on this basis, we could decide at cpufreq init time if we will >> export any overclocking related sysfs entries (or init overclocking at >> all). It would assure clearer code. > > Well, what about users? Don't you want them to be able to decide whether > or not to use "turbo"? I believe Lukasz was saying that we can have two levels of enabling it.. Firstly the driver can say if it supports turbo_mode or not and so will register cpufreq_driver with appropriate parameters.. Now if turbo_mode == true, then sysfs entry will be created by cpufreq core which users can enable/disable... And this is what I had in mind too. >> I think that global cpufreq device tree attribute shall be defined. > > What do you mean by "device tree attribute"? If you mean FDTs as used by > ARM for system configuration description, that wouldn't be portable, because > DTs aren't used for that on the (majority of) x86 systems. So, drivers should pass correct value in boost_mode in struct cpufreq_driver. They get it from DT or is hard coded doesn't matter at all to the core. But yes getting a single name for DT bindings would be good. We should use the same name at that place too: turbo_mode >> The overclocking will be an integral part of the cpufreq framework. > > Well, to be precise, I was thinking about moving the management of the > /sys/devices/system/cpu/cpufreq/boost attribute from acpi-cpufreq to the > code so that other drivers may use it too. Does that make sense to you? Obviously yes. The sysfs related code from acpi-cpufreq should be moved to cpufreq.c and will be functional once cpufreq_driver has boost_mode set as true. >> > Second, I'm not sure if an additional knob for the governor is >> > necessary. It may just use the turbo frequencies if available (and >> > if the governor cannot use them, it simply won't use them). >> >> I cannot agree. It is welcome to be able to enable/disable the feature >> when needed. Turbo frequencies shall not be "available" for use all the >> time. Yes, you can disable that from userspace once your driver said: "I support turbo mode".. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
