On 09/02/2013 04:43 PM, Bartlomiej Zolnierkiewicz wrote: > On Monday, September 02, 2013 04:24:23 PM Daniel Lezcano wrote: >> 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. > > If I believed that it could be handled internally I wouldn't be trying to > add a kernel parameter to handle it.. Would I? ;) > >> Can you shortly describe what happens with the bootloader and AFTR ? > > AFTR just doesn't work with the custom U-Boot version that we are using > (attempts to go into AFTR mode result in lockup) and using the upstream > version of U-Boot is not an option since it doesn't support the hardware > that we are using AFAIK. I also don't know exactly why it doesn't work > (I just suspect that it reuses INFORM registers for some other purposes). You want to add a kernel option as a work around for a bug in U-Boot ? IMO, you should drop the hot potato to the u-boot guys :) >> I guess you are not interested in cpuidle.off=1 because you want cpuidle >> statistics for WFI, right ? > > 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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