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

[ta.omasab@gmail.com (Thomas Abraham)]

Hi Kevin,


On Fri, Aug 29, 2014 at 8:33 PM, Kevin Hilman <khilman@kernel.org> wrote:
> Hi Thomas,
>
> On Fri, Aug 29, 2014 at 5:52 AM, Thomas Abraham <ta.omasab@gmail.com> wrote:
>> Hi Kevin,
>>
>> On Wed, Aug 27, 2014 at 3:55 AM, Kevin Hilman <khilman@linaro.org> wrote:
>>> On Tue, Aug 26, 2014 at 8:15 AM, Kevin Hilman <khilman@linaro.org> wrote:
>>>> On Mon, Aug 25, 2014 at 10:25 PM, Chander Kashyap <k.chander@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.

The branch with the patches that have been used to test cpufreq on
Exynos5800 is available at

https://github.com/exynos-reference/kernel/tree/exynos5-v3.17-rc3-temp-cpufreq

Please let me know if this works or if there are any issues.

Thanks,
Thomas.

>
> Thanks for looking into this,
>
> Kevin