On 09/02/2013 03:48 PM, Bartlomiej Zolnierkiewicz wrote: > On Monday, September 02, 2013 03:18:51 PM Daniel Lezcano wrote: >> On 09/02/2013 11:41 AM, Bartlomiej Zolnierkiewicz wrote: >>> On Monday, September 02, 2013 10:54:17 AM Daniel Lezcano wrote: >>>> On 08/30/2013 12:21 PM, Bartlomiej Zolnierkiewicz wrote: >>>>> Add "cpuidle-exynos.max_states=" parameter to allow user to specify >>>>> the maximum of allowed CPU idle states for ARM EXYNOS cpuidle driver. >>>>> >>>>> This change is needed because C1 state (AFTR mode) is often not able >>>>> to work properly due to incompatibility with some bootloader versions. >>>>> >>>>> Usage examples: >>>>> >>>>> "cpuidle-exynos.max_states=1" disables C1 state (AFTR mode). >>>>> >>>>> "cpuidle-exynos.max_states=0" disables the driver completely. >>>>> >>>>> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> >>>>> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >>>>> Cc: Tomasz Figa <t.figa@xxxxxxxxxxx> >>>>> Cc: Amit Daniel Kachhap <amit.daniel@xxxxxxxxxxx> >>>> >>>> There is a max_cstate option for acpi and intel idle. There is also the >>>> cpuidle.off=1 option. As the semantic is the same, I think adding a >>>> common cpuidle option usable for all the drivers is better. >>> >>> I thought about making the option common for all cpuidle drivers first >>> but due to support for multiple cpuidle drivers on one machine (i.e. >>> big.LITTLE), per-driver option looked like a better approach. >>> >>> Should I make the option common and not worry about multiple drivers on >>> one machine support? >> >> Mmh, that's a good point. >> >> I am not in favor of multiple options spread across the different >> drivers. Furthermore the max_cstate is used in the intel platform to >> 'discover' what states the firmware supports which is not the case of >> the cpuidle ARM drivers (except new PSCI based). This option does not >> really fits well here. >> >> There is the kernel parameter 'cpuidle.off', so disabling the driver is ok. >> >> You converted the cpuidle driver to a platform driver. Isn't possible to >> pass information in the platform data field at boot time to tell AFTR is >> not supported and then act on the 'disabled' field of this state ? > > It might be possible but I don't know where the source of this data would > be, platform specific kernel parameter? It sounds just like moving the code > around and adding superfluous platform->driver code because the similar > kernel parameter to disable just AFTR can be added in cpuidle-exynos driver > as well. It is to prevent to add a new kernel parameter (with the documentation) for a single driver which has a bogus idle state. If that could be handled internally that would be cleaner. Can you shortly describe what happens with the bootloader and AFTR ? I guess you are not interested in cpuidle.off=1 because you want cpuidle statistics for WFI, right ? -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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