Re: [PATCH] drm: mediatek: remove IOMMU_DMA select

From: Robin Murphy
Date: Thu May 12 2016 - 05:24:13 EST


On 11/05/16 21:11, Arnd Bergmann wrote:
We get a harmless build warning when trying to use the mediatek
DRM driver with IOMMU support disabled:

warning: (DRM_MEDIATEK) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT)

However, the IOMMU_DMA symbol is not meant to be used by drivers
at all, and this driver doesn't seem to have a strict dependency
on it other than using the mediatek IOMMU driver that does.

Since we also want to be able to do compile tests with the
driver on other platforms, the IOMMU_DMA symbol should not
be selected here.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
If someone has a better explanation about why the 'select' is here,
let me know, it certainly seems out of place.

Ack - it's neither an IOMMU driver nor a DMA API implementation, so it has no business with IOMMU_DMA. If there's an IOMMU dependency in general it should be on MTK_IOMMU, not underlying implementation details.

Robin.

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 0c06a69d7f04..545973f6b743 100644
--- a/drivers/gpu/drm/mediatek/Kconfig
+++ b/drivers/gpu/drm/mediatek/Kconfig
@@ -7,7 +7,6 @@ config DRM_MEDIATEK
select DRM_KMS_HELPER
select DRM_MIPI_DSI
select DRM_PANEL
- select IOMMU_DMA
select MEMORY
select MTK_SMI
help