Hi Kevin,

On Mon, Aug 25, 2014 at 9:02 PM, Kevin Hilman [off-list ref] wrote:

Hi Chander,

Chander Kashyap [off-list ref] writes:

[...]

quoted

quoted

quoted

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.

quoted

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