exynos5420/arndale-octa: imprecise external aborts on exynos_defconfig

[Kevin Hilman]

On Wed, Sep 17, 2014 at 5:39 PM, Kevin Hilman <khilman at kernel.org> wrote:
> Thomas Abraham <ta.omasab at gmail.com> writes:
>
>> On Thu, Sep 11, 2014 at 12:16 AM, Kevin Hilman <khilman at kernel.org> wrote:
>>> Tyler Baker <tyler.baker at linaro.org> writes:
>>>
>>>> Exynos5420-based Arndale octa boards have recently started failing boot
>>>> tests due to imprecise external aborts.  This only appears to happen
>>>> when using exynos_defconfig and boots fine with multi_v7_defconfig.  The
>>>> issue seems to be intermittent, so is not reliably reproducable and
>>>> difficult to bisect.  Here are a few boot logs from recent
>>>> mainline/linux-next kernels that are failing:
>>>
>>> FYI, I'm seeing the same periodic aborts.  For example, here's my boot
>>> of next-20140910:
>>> http://images.armcloud.us/kernel-ci/next/next-20140910/arm-exynos_defconfig/boot-exynos5420-arndale-octa.html
>>>
>>> However, my userspace is much simpler and doesn't seem to cause a panic,
>>> so my boot tests report passing. (I should fixup my scripts so these
>>> imprecise aborts are reported as a FAIL.)
>>>
>>> I'm glad you pointed out that it happens only with exynos_defconfig and
>>> not multi_v7_defconfig because I noticed that too.  I haven't had the
>>> time to track it any further than that, so maybe the exynos folks can
>>> help track it down from here.
>>>
>>> Thanks for reporting this,
>>>
>>> Kevin
>>
>> Hi Tyler, Kevin,
>>
>> From the bootlog you have shared,
>>
>> [    1.060016] CPU4: failed to come online
>> [    2.070031] CPU5: failed to come online
>> [    3.080049] CPU6: failed to come online
>> [    4.090066] CPU7: failed to come online
>> [    4.090099] Brought up 4 CPUs
>> [    4.090109] SMP: Total of 4 processors activated.
>> [    4.090119] CPU: WARNING: CPU(s) started in wrong/inconsistent
>> modes (primary CPU mode 0x13)
>> [    4.090128] CPU: This may indicate a broken bootloader or firmware.
>>
>> Would it be possible to set max cpus to 1, disable switcher and try
>> again. I don't have a arndale octa board but I have tested mainline
>> kernel with smdk5420 board. It boots all eight CPUs, switcher works
>> fine and there are no imprecise aborts seen.
>
> Sorry for the delay, I'm travelling this week.
>
> FWIW, the same CPU boot failures you hilight above are happening on
> multi_v7_defconfig[1] which is not getting the imprecise abort.  This is
> only happening on exynos_defconfig[2], so I'm curious why you think the
> switcher or NR_CPUS might be the issues.
>
> Anyways, I narrowed this down a bit and discovered it's
> CONFIG_EXYNOS5420_MCPM=y that's the root cause.  If I use
> exynos_defconfig and then disable that option, I don't get any more
> imprecise aborts.

These imprecise aborts are still happening, and preventing running
full userspace.

I'm going to send a patch to disable this CONFIG_EXYNOS5420_MCPM until
someone can figure out what's going on.

Kevin