[PATCH v9 4/6] ARM: Exynos: switch to using generic cpufreq driver for Exynos4210/5250/5420

[Chander Kashyap]

Hi Kevin,

On Mon, Aug 25, 2014 at 9:02 PM, Kevin Hilman <khilman at linaro.org> wrote:
> Hi Chander,
>
> Chander Kashyap <k.chander at samsung.com> writes:
>
> [...]
>
>>>> I'm trying it on the 5800/Chromebook2 and it's not terribly stable.  I'm
>>>> testing along with CPUidle, so there may be some untested interactions
>>>> there as it seems a bit more stable without CPUidle enabled.
>>>>
>>>> I'd love to hear from anyone else that's testing CPUidle and CPUfreq
>>>> together big.LITTLE 5420/5800, with or without the switcher.
>>
>> I have tested this patch series on SMDK5420 with cpuidle (with and
>> without b.L switcher enabled).
>>
>> As of now voltage scaling support is not there in generic big-little
>> cpufreq driver (arm_big_little.c).
>> Hence need to tie arm and kfc voltages to highest level for testing.
>
>> Without this change stability issues are there, but with this change
>> everything is stable.
>
> Can you clarify how you're setting the voltages to ensure stability?

below is the diff :  wip/exynos/integ

--- a/arch/arm/boot/dts/exynos5800-peach-pi.dts
+++ b/arch/arm/boot/dts/exynos5800-peach-pi.dts
@@ -225,7 +225,7 @@

                        buck2_reg: BUCK2 {
                                regulator-name = "vdd_arm";
-                               regulator-min-microvolt = <800000>;
+                               regulator-min-microvolt = <1500000>;
                                regulator-max-microvolt = <1500000>;
                                regulator-always-on;
                                regulator-boot-on;
@@ -260,7 +260,7 @@

                        buck6_reg: BUCK6 {
                                regulator-name = "vdd_kfc";
-                               regulator-min-microvolt = <800000>;
+                               regulator-min-microvolt = <1500000>;
                                regulator-max-microvolt = <1500000>;
                                regulator-always-on;
                                regulator-boot-on;

>
> Tomasz, I didn't mean to suggest this isn't ready for mainline.  For the
> 5420/5800 it seems cpufreq support is a new feature, so this isn't a
> regression against previous (mainline) behavior.  Maybe the big.LITTLE
> cpufreq support should've been separated out from the cleanup since it's
> more of a new feature, but that's up to you.
>
> Kevin
>
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regards,
Chander