[PATCH] drm/mediatek: Do not select IOMMU_DMA

[PATCH] drm/mediatek: Do not select IOMMU_DMA

[Thierry Reding]

From: Thierry Reding <treding@nvidia.com>

The IOMMU_DMA symbol depends on IOMMU_API, but DRM_MEDIATEK itself does
not have a dependency on that symbol.

Furthermore the driver doesn't use any of the code enabled by IOMMU_DMA
and the only IOMMU API call that it uses, iommu_present(), has a dummy
implementation if IOMMU_API isn't selected. Effectively there really is
no build time dependency on the IOMMU API.

Because of all of the above, the dependency on IOMMU_DMA or IOMMU_API
doesn't belong in the Mediatek DRM driver, but is really a matter of
platform integration. A default configuration should be enabling IOMMU
support if the driver should take advantage of it.

Note that the driver currently defers probe indefinitely if no IOMMU is
registered on the parent bus. There's really no reason for it to do that
since the driver exclusively uses the DMA API to allocate and map memory
and should therefore work even if no IOMMU is registered and for example
the contiguous memory allocator is enabled instead.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/gpu/drm/mediatek/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/Kconfig b/drivers/gpu/drm/mediatek/Kconfig
index eeefc971801a..9eefecedc3da 100644
--- a/drivers/gpu/drm/mediatek/Kconfig
+++ b/drivers/gpu/drm/mediatek/Kconfig
@@ -6,7 +6,6 @@ config DRM_MEDIATEK
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select DRM_PANEL
-	select IOMMU_DMA
 	select MEMORY
 	select MTK_SMI
 	help
-- 
2.8.3

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