Re: [PATCH] ARM: exynos_defconfig: Enable big.LITTLE CPUidle support

From: Krzysztof Kozlowski
Date: Sat Aug 29 2015 - 05:02:15 EST


W dniu 28.08.2015 o 17:16, Javier Martinez Canillas pisze:
> Some Exynos big.LITTLE boards (i.e: Exynos5420 and Exynos5800 based
> Chromebooks) have proper firmware that allow the big.LITTLE CPUidle
> driver to work correctly, so enable support for this.
>
> Signed-off-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
>
> ---
> Kukjin and Krzysztof,
>
> As you know there are other boards like the Exynos5422 based Odroid XU{3,4}
> whose firmware is broken due leaving CCI in secure mode which means that the
> kernel MCPM support can't properly manage CCI.
>
> So if you pick this patch, it should be tested in kernelci before appearing
> in linux-next to prevent any boot issues.
>
> But if that happens, I believe that is better to do a fix / workaround in
> those broken platforms since nothing prevents users to enable this option
> anyways. For example the CCI device node could be disabled in the DTS.
>
> arch/arm/configs/exynos_defconfig | 1 +
> 1 file changed, 1 insertion(+)

On Odroid XU3L (next-20150828, Hardkernel u-boot) boot hangs just after:

[ 2.568650] dwmmc_exynos 12200000.mmc: num-slots property not found,
assuming 1 slot is available

... so no. NACK :). First the boards, firmware, bootloader or kernel
code have to be fixed.

Best regards,
Krzysztof

>
> diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
> index 729e2fae3e58..228ee945b8ed 100644
> --- a/arch/arm/configs/exynos_defconfig
> +++ b/arch/arm/configs/exynos_defconfig
> @@ -30,6 +30,7 @@ CONFIG_CPU_FREQ=y
> CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
> CONFIG_CPUFREQ_DT=y
> CONFIG_CPU_IDLE=y
> +CONFIG_ARM_BIG_LITTLE_CPUIDLE=y
> CONFIG_ARM_EXYNOS_CPUIDLE=y
> CONFIG_VFP=y
> CONFIG_NEON=y
>

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