gpu: host1x: Detach Host1x from IOMMU DMA domain on arm32

Host1x is getting attached to an implicit IOMMU DMA domain if
CONFIG_ARM_DMA_USE_IOMMU=y. Since Host1x driver manages IOMMU by
itself, Host1x device must be detached from the implicit domain using
arch-specific IOMMU-API.

Signed-off-by: Dmitry Osipenko <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>

drivers/gpu/host1x/dev.c

···
 #include <trace/events/host1x.h>
 #undef CREATE_TRACE_POINTS
 
+#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
+#include <asm/dma-iommu.h>
+#endif
+
 #include "bus.h"
 #include "channel.h"
 #include "debug.h"
···
 		dev_err(&pdev->dev, "failed to get reset: %d\n", err);
 		return err;
 	}
-
+#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
+	if (host->dev->archdata.mapping) {
+		struct dma_iommu_mapping *mapping =
+				to_dma_iommu_mapping(host->dev);
+		arm_iommu_detach_device(host->dev);
+		arm_iommu_release_mapping(mapping);
+	}
+#endif
 	if (IS_ENABLED(CONFIG_TEGRA_HOST1X_FIREWALL))
 		goto skip_iommu;