Linux-next, Exynos Octa boot fail, bisected to: "drm/exynos: remove drm_iommu_attach_device_if_possible"

[Joonyoung Shim]

On 07/21/2015 10:19 PM, Krzysztof Kozlowski wrote:
> Hi,
> 
> Today's linux-next (next-20150721) encounters boot failures on Exynos
> Octa (Exynos5422) based boards. The boards hangs. I bisected it to:
> 
> d80167b85024982c5f18d0481a5c248100360118 is the first bad commit
> commit d80167b85024982c5f18d0481a5c248100360118
> Author: Joonyoung Shim <jy0922.shim at samsung.com>
> Date:   Thu Jul 2 21:49:39 2015 +0900
> 
>     drm/exynos: remove drm_iommu_attach_device_if_possible
> 
>     Already drm_iommu_attach_device checks whether support iommu internally.
>     It should clear channels always regardless iommu support. We didn't know
>     because we can detect the problem when iommu is enabled, so we don't
>     have to use drm_iommu_attach_device_if_possible and then we can remove
>     drm_iommu_attach_device_if_possible and clear_channels function pointer.
> 
>     Signed-off-by: Joonyoung Shim <jy0922.shim at samsung.com>
>     Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>
>     Signed-off-by: Inki Dae <inki.dae at samsung.com>
> 
> :040000 040000 83379efbf4960f58d680371628ec04387935bd53
> da03c338b88e7cb6bda895b3dd52d78d9b6eba30 M drivers
> 
> 
> Config: exynos
> Boot log from Odroid XU3-Lite attached.
> 
> Any hints or ideas?

The point that hangs is when accesses fimd register in
fimd_clear_channels function, so i doubt clock setting for fimd.

It's gone something that hangs after i enable gating for ACLK_200_DISP1
clock.

If ACLK_200_DISP1 clock needs for fimd really, i'm thinking how can it
support. Any ideas?

Thanks.