Re: [PATCH 1/1] ARM: exynos_defconfig: Disable IOMMU support

From: Marek Szyprowski
Date: Wed Mar 04 2015 - 03:50:29 EST


Hello,

On 2015-03-03 21:36, Kevin Hilman wrote:
Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx> writes:

Enabling Exynos DRM IOMMU support for Exynos is currently broken and
causes a BUG on exynos-iommu driver. This was not an issue since the
options was disabled in exynos_defconfig but after commit 8dcc14f82f06
("drm/exynos: IOMMU support should not be selectable by user"), it is
selected if EXYNOS_IOMMU is enabled which is in exynos_defconfig.

So a kernel built using exynos_defconfig after the mentioned commit
fails to boot [0]. Disable IOMMU support in Exynos defconfig until
things get sorted out.
So some other exynos boards started failing in next-20150303[1], and
appear are DRM failures.

Interestingly, (re)enabling CONFIG_EXYNOS_IOMMU for these cause things to
work again. Even more intersting, with IOMMU enabled, peach-pi is

I'm starting to think it's the DRM driver that needs to be disabled
until it actually gets some testing, rathre than disabling IOMMU.

Well, this only shows that broken patch has been merged to exynos-drm-next
kernel tree. I think that we should keep Exynos DRM enabled and give Exynos
DRM developers a chance to fix their stuff and then test their stuff.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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