Hi,
Am 19.08.2014 14:01, schrieb Marek Szyprowski:
On 2014-08-19 13:39, Andreas Färber wrote:
I'm working on 5250 based Spring Chromebook and noticed that v3.17-rc1 got some more iommu support. With the new CONFIG_DRM_EXYNOS_IOMMU=y my machine stops booting. So I'm wondering, is any of this a fix for 3.17, or is all of this "unrelated" -next material?
This is probably a side effect of patch 3170447c1f264d51b8d1f3898bf2588588a64fdc ("iommu/exynos: Select ARM_DMA_USE_IOMMU"). It added selection of ARM_DMA_USE_IOMMU symbol, on which IOMMU support in Exynos DRM subsystem depends. However selecting this symbol is all that this patch does, without providing any code code which implements real support for ARM DMA IOMMU integration, which is needed by Exynos DRM driver. Please disable CONFIG_DRM_EXYNOS_IOMMU in kernel .config and your system should be bootable again.
Yes, that's what my report implied. :)
I'm bringing this up for -rc2 though: It sounds as if that option should remain unavailable until the required code is in? Thanks.
Also, are you or someone working on the respective DT changes for Exynos5?
I can prepare DT changes for Exynos5 as well, but first I wanted to clarify if everyone involved in generic IOMMU bindings and Exynos IOMMU driver agrees on my proposal.
Sure. I'm updating my old spring-bridge.v6 branch [1] to 3.17-rc1 [2], which involves three drm bridge patches rebased onto the new drm panel prepare/unprepare infrastructure plus two LVDS DT patches in addition to the IOMMU patches. That old branch included DT changes for 5250 in "ARM: dts: add System MMU nodes of Exynos SoCs", but that'll probably need updating for the new bindings.
Regards, Andreas
[1] https://github.com/afaerber/linux/commits/spring-bridge.v6 [2] https://github.com/afaerber/linux/commits/spring-next