drm/exynos: Consider fallback option to allocation fail

To address the case where physically contiguous memory
MAY NOT be a mandatory requirement for framebuffer for
the application calling exynos_drm_gem_dumb_create,
the patch adds a feature to get non physically contiguous
memory for framebuffer, if physically contiguous memory
allocation fails and if IOMMU is supported.
Signed-off-by: Vikas Sajjan <vikas.sajjan@linaro.org>
Signed-off-by: Arun Kumar <arun.kk@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_gem.c

@@ -18,6 +18,7 @@
 #include "exynos_drm_drv.h"
 #include "exynos_drm_gem.h"
 #include "exynos_drm_buf.h"
+#include "exynos_drm_iommu.h"
 
 static unsigned int convert_to_vm_err_msg(int msg)
 {
@@ -666,6 +667,18 @@ int exynos_drm_gem_dumb_create(struct drm_file *file_priv,
 
 	exynos_gem_obj = exynos_drm_gem_create(dev, EXYNOS_BO_CONTIG |
 						EXYNOS_BO_WC, args->size);
+	/*
+	 * If physically contiguous memory allocation fails and if IOMMU is
+	 * supported then try to get buffer from non physically contiguous
+	 * memory area.
+	 */
+	if (IS_ERR(exynos_gem_obj) && is_drm_iommu_supported(dev)) {
+		dev_warn(dev->dev, "contiguous FB allocation failed, falling back to non-contiguous\n");
+		exynos_gem_obj = exynos_drm_gem_create(dev,
+					EXYNOS_BO_NONCONTIG | EXYNOS_BO_WC,
+					args->size);
+	}
+
 	if (IS_ERR(exynos_gem_obj))
 		return PTR_ERR(exynos_gem_obj);