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

[Kevin Hilman <khilman@kernel.org>]

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