linux-kernel - [PATCH] exynos-drm: Fix display manager failing to start without IOMMU problem

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Date:	Wed, 10 Aug 2016 11:30:51 -0600
From:	Shuah Khan <shuahkh@....samsung.com>
To:	inki.dae@...sung.com, jy0922.shim@...sung.com,
	sw0312.kim@...sung.com, kyungmin.park@...sung.com,
	airlied@...ux.ie, kgene@...nel.org, k.kozlowski@...sung.com
Cc:	Shuah Khan <shuahkh@....samsung.com>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] exynos-drm: Fix display manager failing to start without IOMMU problem

Fix exynos_drm_gem_create_ioctl() attempts to allocate non-contiguous GEM
memory without IOMMU. In this case, there is no point in attempting to
allocate non-contiguous memory, only to return error during the next step
from exynos_drm_framebuffer_init() which leads to display manager failing
to start.

Check if non-contiguous GEM memory is requested without IOMMU. If so,
allocate contiguous GEM memory to help display manager start.

Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_gem.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 4c4cb0e..4719116 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -266,6 +266,20 @@ int exynos_drm_gem_create_ioctl(struct drm_device *dev, void *data,
 	struct exynos_drm_gem *exynos_gem;
 	int ret;
 
+	/*
+	 * Check if non-contiguous GEM memory is requested without IOMMU.
+	 * If so, allocate contiguous GEM memory.
+	 *
+	 * There is no point in attempting to allocate non-contiguous memory,
+	 * only to return error from exynos_drm_framebuffer_init() which leads
+	 * to display manager failing to start.
+	*/
+	if (!is_drm_iommu_supported(dev) &&
+	    (args->flags & EXYNOS_BO_NONCONTIG)) {
+		args->flags &= ~EXYNOS_BO_NONCONTIG;
+		args->flags |= EXYNOS_BO_CONTIG;
+	}
+
 	exynos_gem = exynos_drm_gem_create(dev, args->flags, args->size);
 	if (IS_ERR(exynos_gem))
 		return PTR_ERR(exynos_gem);
-- 
2.7.4