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

[Kevin Hilman]

Hi Thomas,

On Fri, Aug 29, 2014 at 5:52 AM, Thomas Abraham <ta.omasab at gmail.com> wrote:
> Hi Kevin,
>
> On Wed, Aug 27, 2014 at 3:55 AM, Kevin Hilman <khilman at linaro.org> wrote:
>> On Tue, Aug 26, 2014 at 8:15 AM, Kevin Hilman <khilman at linaro.org> wrote:
>>> On Mon, Aug 25, 2014 at 10:25 PM, Chander Kashyap <k.chander at samsung.com> wrote:
>>
>> [...]
>>
>>>>>
>>>>> Can you clarify how you're setting the voltages to ensure stability?
>>>>
>>>> below is the diff :  wip/exynos/integ
>>>
>>> Thanks.
>>>
>>> I've applied your patch, and bootup shows vdd_arm and vdd_kfc at
>>> 1500mV, but still when booting with cpuidle enabled (bL switcher
>>> disabled), I'm seeing lockups with no kernel output.  With CPUidle
>>> disabled, things are pretty stable.
>>>
>>> What tree are you using to test this out on 5420?  I'm using mainline
>>> v3.17-rc1 + DT patch for CPUidle and this cpufreq series.  See my
>>> wip/exynos/integ branch at
>>> git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux.git.
>>
>> I mis-stated this.  Actually my tree is based on the v3.17-rc1 branch
>> of the exynos-reference tree[1] + the above mentioned patches for
>> cpuidle and cpufreq.
>>
>> Also, I've narrowed down the instability a bit, and it's not related
>> to CPUidle.  I can now trigger a boot hang even without CPUidle
>> enabled.  Here's a quick way to cause a boot lockup. With the switcher
>> disabled, I enable CPUfreq and set the default governor to
>> performance.  As soon as cpufreq driver loads, it tries to use the top
>> frequences for both clusters, and it hangs.
>>
>> Selectively disabling frequencies, I narrowed it down to the 1.3GHz
>> and 1.2GHz frequencies of the little cluster.  With these commented
>> out in the DT, it will fully boot with the performance governor
>> enabled.
>>
>> So that leads to the question.  Are all of the operating points in
>> exynos5420.dtsi valid for exynos5800, and have they been validated?
>
> I tried to recreate the boot lockup issue using the same steps you
> listed above for the Exynos5800 peach-pi platform (Chromebook2), but I
> do not see any issues. I can see both clusters with max clock speed
> after boot (1.8GHz and 1.3GHz).
>
> I am using v3.17-rc2 + CPUFreq Patches + max77802 regulator support
> patches for Chromebook2 + temp hack to set A15 voltage to 1.35V and A7
> voltage to 1.3V.

Can you share your branch and temp hack(s) as well as your defconfig?

I'm using the v3.17-rc1 branch from the exynos tree (which includes
the max77802 series) but also has a bunch of other stuff which may be
causing the issue.

It would be good if I can reproduce your exact tree/branch and see if
I still have the same problem.

Thanks for looking into this,

Kevin