screen blank causing lockup in exynos-reference/exynos5-v3.18-rc2

screen blank causing lockup in exynos-reference/exynos5-v3.18-rc2

[Kevin Hilman]

As I'm hunting around trying to figure out how to make exynos-drm work
with v3.18 or linux-next, I noticed there was an exynos5-v3.18-rc2
branch in the exynos-reference tree[1], so I gave that a spin on my
exynos5800-peach-pi.

It seemed to work OK, but I noticed that as soon as the screen blanked
after timeout, typing on the serial console would still work, but any
typing on the keyboard caused a silent lockup, with no output on the
serial console.

I was able to easily reproduce this by doing

  # echo 3 > /sys/class/graphics/fb0/blank

on the serial console, verifying I could still type on the serial
console. Then, touch any key on the physical keyboard and then I can
no longer type on the serial console, ping the target, etc.

Kevin

[1] https://github.com/exynos-reference/kernel.git

Re: screen blank causing lockup in exynos-reference/exynos5-v3.18-rc2

[Kevin Hilman]

Hi Ajay,

AJAY KUMAR RAMAKRISHNA SHYMALAMMA <ajaykumar.rs@samsung.com> writes:

> I tried to reproduce the issue which you reported,
>
> but I am sorry I am not able to reproduce it.
>
> I tried with my patches for DRM on top of Linux-next.

I don't see the issue on linux-next either.  As I mentioned in the
original post, I only see it on the v3.18 branch in the exynos-reference
tree.

Kevin

Re: screen blank causing lockup in exynos-reference/exynos5-v3.18-rc2

[Vivek Gautam]

Hi Kevin,


On Sat, Nov 22, 2014 at 12:53 AM, Kevin Hilman <khilman@kernel.org> wrote:
> Hi Ajay,
>
> AJAY KUMAR RAMAKRISHNA SHYMALAMMA <ajaykumar.rs@samsung.com> writes:
>
>> I tried to reproduce the issue which you reported,
>>
>> but I am sorry I am not able to reproduce it.
>>
>> I tried with my patches for DRM on top of Linux-next.
>
> I don't see the issue on linux-next either.  As I mentioned in the
> original post, I only see it on the v3.18 branch in the exynos-reference
> tree.

While checking the issue along with Ajay on "exynos5-v3.18-rc2" branch
on exynos-reference
tree, we found out the culprit to be FIMD-SYSMMU.
The IOMMU on exynos systems is still WIP, and that's the reason it is
disabled in
exynos_defconfig too.
So we have a small workaround in this branch to stop using FIMD-SYSMMUs.

Now, at the bootup time things are OK, since the FIMD-SMMU clocks
(CLK_SMMU_FIMD**)
are still available. But after bootup all unused clocks are disabled
(since we don't want to
use clk_ignore_unused in boot arguments), and the consequent blanking-unblanking
causes the system to hang.

So we have pushed a patch on the same branch "exynos5-v3.18-rc2" which sets
CLK_IGNORE_UNUSED flag for these SMMU_FIMD** clocks.

This fixes the issue of hang what we were seeing.

There's another branch "exynos5-v3.18-rc5" available, and we have
pushed the same patch
on that branch too.
Please test on your side, and do let us know if things are working fine for you.



-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India

Re: screen blank causing lockup in exynos-reference/exynos5-v3.18-rc2

[Kevin Hilman]

Hi Vivek,

Vivek Gautam <gautamvivek1987@gmail.com> writes:

> On Sat, Nov 22, 2014 at 12:53 AM, Kevin Hilman <khilman@kernel.org> wrote:
>> Hi Ajay,
>>
>> AJAY KUMAR RAMAKRISHNA SHYMALAMMA <ajaykumar.rs@samsung.com> writes:
>>
>>> I tried to reproduce the issue which you reported,
>>>
>>> but I am sorry I am not able to reproduce it.
>>>
>>> I tried with my patches for DRM on top of Linux-next.
>>
>> I don't see the issue on linux-next either.  As I mentioned in the
>> original post, I only see it on the v3.18 branch in the exynos-reference
>> tree.
>
> While checking the issue along with Ajay on "exynos5-v3.18-rc2" branch
> on exynos-reference
> tree, we found out the culprit to be FIMD-SYSMMU.
> The IOMMU on exynos systems is still WIP, and that's the reason it is
> disabled in
> exynos_defconfig too.
> So we have a small workaround in this branch to stop using FIMD-SYSMMUs.
>
> Now, at the bootup time things are OK, since the FIMD-SMMU clocks
> (CLK_SMMU_FIMD**)
> are still available. But after bootup all unused clocks are disabled
> (since we don't want to
> use clk_ignore_unused in boot arguments), and the consequent blanking-unblanking
> causes the system to hang.
>
> So we have pushed a patch on the same branch "exynos5-v3.18-rc2" which sets
> CLK_IGNORE_UNUSED flag for these SMMU_FIMD** clocks.
>
> This fixes the issue of hang what we were seeing.
>
> There's another branch "exynos5-v3.18-rc5" available, and we have
> pushed the same patch
> on that branch too.
> Please test on your side, and do let us know if things are working fine for you.

I've tested the -rc5 branch, and I'm not seeing this issue anymore.

Thanks,

Kevin