exynos5420/arndale-octa: imprecise external aborts on exynos_defconfig

[b.zolnierkie@samsung.com (Bartlomiej Zolnierkiewicz)]

Hi,

On Wednesday, September 17, 2014 05:39:29 PM Kevin Hilman wrote:
> Thomas Abraham <ta.omasab@gmail.com> writes:
> 
> > On Thu, Sep 11, 2014 at 12:16 AM, Kevin Hilman <khilman@kernel.org> wrote:
> >> Tyler Baker <tyler.baker@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

Which "max cpus" do you mean?  For NR_CPUS the lower limit is 2.

> > 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.

I have exactly the same issue with Exynos5420 Arndale Octa.

CONFIG_EXYNOS5420_MCPM was enabled by commit fc3791f3a95d
("ARM: exynos_defconfig: Update exynos_defconfig") which
get merged into v3.17-rc1.  It seems that this part of
the patch should be reverted for the final v3.17 kernel.

> Kevin
> 
> [1] http://images.armcloud.us/kernel-ci/mainline/v3.17-rc5-25-g8ba4caf/arm-multi_v7_defconfig/boot-exynos5420-arndale-octa.html
> [2] http://images.armcloud.us/kernel-ci/mainline/v3.17-rc5-25-g8ba4caf/arm-exynos_defconfig/boot-exynos5420-arndale-octa.html

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics