linux-kernel - [PATCH 16/32] powerpc/dma: remove the iommu fallback for coherent allocations

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Message-Id: <20190213070133.11259-17-hch@lst.de>
Date:   Wed, 13 Feb 2019 08:01:17 +0100
From:   Christoph Hellwig <hch@....de>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Olof Johansson <olof@...om.net>
Cc:     linuxppc-dev@...ts.ozlabs.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org,
        Christian Zigotzky <chzigotzky@...osoft.de>
Subject: [PATCH 16/32] powerpc/dma: remove the iommu fallback for coherent allocations

All iommu capable platforms now always use the iommu code with the
internal bypass, so there is not need for this magic anymore.

Signed-off-by: Christoph Hellwig <hch@....de>
Tested-by: Christian Zigotzky <chzigotzky@...osoft.de>
---
 arch/powerpc/Kconfig      |  4 ---
 arch/powerpc/kernel/dma.c | 68 ++-------------------------------------
 2 files changed, 2 insertions(+), 70 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 08908219fba9..8a4ae675c9ba 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -119,9 +119,6 @@ config GENERIC_HWEIGHT
 	bool
 	default y
 
-config ARCH_HAS_DMA_SET_COHERENT_MASK
-        bool
-
 config PPC
 	bool
 	default y
@@ -130,7 +127,6 @@ config PPC
 	#
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
-	select ARCH_HAS_DMA_SET_COHERENT_MASK
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index 5eca02315b2e..9def69c8f602 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -115,51 +115,6 @@ void __dma_nommu_free_coherent(struct device *dev, size_t size,
 }
 #endif /* !CONFIG_NOT_COHERENT_CACHE */
 
-static void *dma_nommu_alloc_coherent(struct device *dev, size_t size,
-				       dma_addr_t *dma_handle, gfp_t flag,
-				       unsigned long attrs)
-{
-	struct iommu_table *iommu;
-
-	/* The coherent mask may be smaller than the real mask, check if
-	 * we can really use the direct ops
-	 */
-	if (dma_nommu_dma_supported(dev, dev->coherent_dma_mask))
-		return __dma_nommu_alloc_coherent(dev, size, dma_handle,
-						   flag, attrs);
-
-	/* Ok we can't ... do we have an iommu ? If not, fail */
-	iommu = get_iommu_table_base(dev);
-	if (!iommu)
-		return NULL;
-
-	/* Try to use the iommu */
-	return iommu_alloc_coherent(dev, iommu, size, dma_handle,
-				    dev->coherent_dma_mask, flag,
-				    dev_to_node(dev));
-}
-
-static void dma_nommu_free_coherent(struct device *dev, size_t size,
-				     void *vaddr, dma_addr_t dma_handle,
-				     unsigned long attrs)
-{
-	struct iommu_table *iommu;
-
-	/* See comments in dma_nommu_alloc_coherent() */
-	if (dma_nommu_dma_supported(dev, dev->coherent_dma_mask))
-		return __dma_nommu_free_coherent(dev, size, vaddr, dma_handle,
-						  attrs);
-	/* Maybe we used an iommu ... */
-	iommu = get_iommu_table_base(dev);
-
-	/* If we hit that we should have never allocated in the first
-	 * place so how come we are freeing ?
-	 */
-	if (WARN_ON(!iommu))
-		return;
-	iommu_free_coherent(iommu, size, vaddr, dma_handle);
-}
-
 int dma_nommu_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
 			     void *cpu_addr, dma_addr_t handle, size_t size,
 			     unsigned long attrs)
@@ -262,8 +217,8 @@ static inline void dma_nommu_sync_single(struct device *dev,
 #endif
 
 const struct dma_map_ops dma_nommu_ops = {
-	.alloc				= dma_nommu_alloc_coherent,
-	.free				= dma_nommu_free_coherent,
+	.alloc				= __dma_nommu_alloc_coherent,
+	.free				= __dma_nommu_free_coherent,
 	.mmap				= dma_nommu_mmap_coherent,
 	.map_sg				= dma_nommu_map_sg,
 	.unmap_sg			= dma_nommu_unmap_sg,
@@ -280,25 +235,6 @@ const struct dma_map_ops dma_nommu_ops = {
 };
 EXPORT_SYMBOL(dma_nommu_ops);
 
-int dma_set_coherent_mask(struct device *dev, u64 mask)
-{
-	if (!dma_supported(dev, mask)) {
-		/*
-		 * We need to special case the direct DMA ops which can
-		 * support a fallback for coherent allocations. There
-		 * is no dma_op->set_coherent_mask() so we have to do
-		 * things the hard way:
-		 */
-		if (get_dma_ops(dev) != &dma_nommu_ops ||
-		    get_iommu_table_base(dev) == NULL ||
-		    !dma_iommu_dma_supported(dev, mask))
-			return -EIO;
-	}
-	dev->coherent_dma_mask = mask;
-	return 0;
-}
-EXPORT_SYMBOL(dma_set_coherent_mask);
-
 int dma_set_mask(struct device *dev, u64 dma_mask)
 {
 	if (ppc_md.dma_set_mask)
-- 
2.20.1