linux-kernel - [PATCH 4.4 026/105] drm/exynos: gem: Drop NONCONTIG flag for buffers allocated without IOMMU

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Date:   Fri, 15 Dec 2017 10:44:24 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Inki Dae <inki.dae@...sung.com>
Subject: [PATCH 4.4 026/105] drm/exynos: gem: Drop NONCONTIG flag for buffers allocated without IOMMU

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marek Szyprowski <m.szyprowski@...sung.com>

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.

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Inki Dae <inki.dae@...sung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -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;