drm/exynos: iommu: detach from default dma-mapping domain on init

This patch adds code, which detach sub-device nodes from default iommu
domain if such has been configured. This lets Exynos DRM driver to properly
attach sub-devices to its own, common for all sub-devices domain.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_iommu.c

@@ -100,6 +100,9 @@ int drm_iommu_attach_device(struct drm_device *drm_dev,
 
 	dma_set_max_seg_size(subdrv_dev, 0xffffffffu);
 
+	if (subdrv_dev->archdata.mapping)
+		arm_iommu_detach_device(subdrv_dev);
+
 	ret = arm_iommu_attach_device(subdrv_dev, dev->archdata.mapping);
 	if (ret < 0) {
 		DRM_DEBUG_KMS("failed iommu attach.\n");