[PATCH] drm/nouveau/platform: fix compilation if !CONFIG_IOMMU

[Alexandre Courbot <acourbot@nvidia.com>]

The lack of IOMMU API support can make nouveau_platform_probe_iommu()
fail to compile because struct iommu_ops is then empty. Fix this by
skipping IOMMU probe in that case - lack of IOMMU on platform devices
is sub-optimal, but is not an error.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
This is an alternative to https://lkml.org/lkml/2015/5/19/484. Most users
of Nouveau do not care about IOMMU support, so we should not impose that
option on them.

 drm/nouveau/nouveau_platform.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_platform.c b/drivers/gpu/drm/nouveau/nouveau_platform.c
index 775277f1edb0..dcfbbfaf1739 100644
--- a/drivers/gpu/drm/nouveau/nouveau_platform.c
+++ b/drivers/gpu/drm/nouveau/nouveau_platform.c
@@ -92,6 +92,8 @@ static int nouveau_platform_power_down(struct nouveau_platform_gpu *gpu)
 	return 0;
 }
 
+#if IS_ENABLED(CONFIG_IOMMU_API)
+
 static void nouveau_platform_probe_iommu(struct device *dev,
 					 struct nouveau_platform_gpu *gpu)
 {
@@ -158,6 +160,20 @@ static void nouveau_platform_remove_iommu(struct device *dev,
 	}
 }
 
+#else
+
+static void nouveau_platform_probe_iommu(struct device *dev,
+					 struct nouveau_platform_gpu *gpu)
+{
+}
+
+static void nouveau_platform_remove_iommu(struct device *dev,
+					  struct nouveau_platform_gpu *gpu)
+{
+}
+
+#endif
+
 static int nouveau_platform_probe(struct platform_device *pdev)
 {
 	struct nouveau_platform_gpu *gpu;
-- 
2.4.0