Thread (9 messages) 9 messages, 6 authors, 2014-09-01
STALE4299d

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

From: Tomasz Figa <hidden>
Date: 2014-08-25 15:56:36
Also in: linux-arm-kernel, linux-samsung-soc

Possibly related (same subject, not in this thread)

On 25.08.2014 17:32, Kevin Hilman wrote:
Hi Chander,

Chander Kashyap [off-list ref] writes:

[...]
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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?

Tomasz, I didn't mean to suggest this isn't ready for mainline.
I haven't said that either. I'd just like to know in what state this
series is in case of those SoCs. However, if there are stability issues
on them, there is also a chance that the same is true for other boards.

Anyway, we're early in releasy cycle, so probably we could get better
test coverage with this series in linux-next.

Kukjin, Viresh, how would you want to proceed with merging it? It
touches mach-exynos, cpufreq and samsung-clk, so it is non-trivial to
merge. However as far as I can see the cpufreq-related changes are just
a number of full file deletes and minor Makefile/Kconfig updates. It
will be more difficult with mach-exynos changes, as they are more likely
to produce conflict.

The only solution that comes to my mind is that I first apply patches 1
and 2, create a stable branch for Kukjin, then he applies patches 3, 4,
and 5 and creates a stable branch for me, on top of which I apply patch 6.

Best regards,
Tomasz
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