[PATCH v2] gpu: host1x: Detach Host1x from IOMMU DMA domain on arm32

[Dmitry Osipenko]

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. Note that this works only for arm32 and not
for arm64, which will remain broken if CONFIG_IOMMU_DMA is enabled.

Signed-off-by: Dmitry Osipenko <digetx at gmail.com>
---

Changelog:

v2: Correctly placed the detachment code, now Host1x is detached regardless
    of the firewall state.

 drivers/gpu/host1x/dev.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index d88073e7d22d..c8a56c11a63a 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -29,6 +29,10 @@
 #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"
@@ -217,7 +221,14 @@ static int host1x_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "failed to get reset: %d\n", err);
 		return err;
 	}
-
+#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
+	if (pdev->dev->archdata.mapping) {
+		struct dma_iommu_mapping *mapping =
+				to_dma_iommu_mapping(pdev->dev);
+		arm_iommu_detach_device(pdev->dev);
+		arm_iommu_release_mapping(mapping);
+	}
+#endif
 	if (IS_ENABLED(CONFIG_TEGRA_HOST1X_FIREWALL))
 		goto skip_iommu;
 
-- 
2.18.0