Patch "drm/exynos: gem: Drop NONCONTIG flag for buffers allocated without IOMMU" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

drm/exynos: gem: Drop NONCONTIG flag for buffers allocated without IOMMU

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-exynos-gem-drop-noncontig-flag-for-buffers-allocated-without-iommu.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Marek Szyprowski <[email protected]>
Date: Wed, 22 Nov 2017 14:14:47 +0100
Subject: drm/exynos: gem: Drop NONCONTIG flag for buffers allocated without IOMMU

From: Marek Szyprowski <[email protected]>

commit 120a264f9c2782682027d931d83dcbd22e01da80 upstream.

When no IOMMU is available, all GEM buffers allocated by Exynos DRM driver are contiguous, because of the underlying dma_alloc_attrs() function provides only such buffers. In such case it makes no sense to keep BO_NONCONTIG flag for the allocated GEM buffers. This allows to avoid failures for buffer contiguity checks in the subsequent operations on GEM objects.

---
 drivers/gpu/drm/exynos/exynos_drm_gem.c |    9 +++++++++
 1 file changed, 9 insertions(+)

@@ -245,6 +245,15 @@ struct exynos_drm_gem *exynos_drm_gem_cr
 	if (IS_ERR(exynos_gem))
 		return exynos_gem;
 
+	if (!is_drm_iommu_supported(dev) && (flags & EXYNOS_BO_NONCONTIG)) {
+		/*
+		 * when no IOMMU is available, all allocated buffers are
+		 * contiguous anyway, so drop EXYNOS_BO_NONCONTIG flag
+		 */
+		flags &= ~EXYNOS_BO_NONCONTIG;
+		DRM_WARN("Non-contiguous allocation is not supported without IOMMU, falling back to contiguous buffer\n");
+	}
+
 	/* set memory type and cache attribute from user side. */
 	exynos_gem->flags = flags;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/drm-exynos-gem-drop-noncontig-flag-for-buffers-allocated-without-iommu.patch