take the bus_dma_limit into account on arm

take the bus_dma_limit into account on arm

[Christoph Hellwig]

Hi Russell,

this series fixes the arm dma coherent allocator to take the bus dma
mask into account, similar to what other architectures do.  Without
this devices that support 64-bit mask, but are limited by the
interconnect won't work properly.
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[PATCH 1/3] ARM/dma-mapping: remove get_coherent_dma_mask

[Christoph Hellwig]

The core DMA code already checks for valid DMA masks earlier on, and
doesn't allow NULL struct device pointers.  Remove the now not required
checks.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/mm/dma-mapping.c | 41 ++++-----------------------------------
 1 file changed, 4 insertions(+), 37 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 9414d72f664b..72ddc3d0f5eb 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -219,7 +219,7 @@ const struct dma_map_ops arm_coherent_dma_ops = {
 };
 EXPORT_SYMBOL(arm_coherent_dma_ops);
 
-static int __dma_supported(struct device *dev, u64 mask, bool warn)
+static int __dma_supported(struct device *dev, u64 mask)
 {
 	unsigned long max_dma_pfn = min(max_pfn - 1, arm_dma_pfn_limit);
 
@@ -227,41 +227,11 @@ static int __dma_supported(struct device *dev, u64 mask, bool warn)
 	 * Translate the device's DMA mask to a PFN limit.  This
 	 * PFN number includes the page which we can DMA to.
 	 */
-	if (dma_to_pfn(dev, mask) < max_dma_pfn) {
-		if (warn)
-			dev_warn(dev, "Coherent DMA mask %#llx (pfn %#lx-%#lx) covers a smaller range of system memory than the DMA zone pfn 0x0-%#lx\n",
-				 mask,
-				 dma_to_pfn(dev, 0), dma_to_pfn(dev, mask) + 1,
-				 max_dma_pfn + 1);
+	if (dma_to_pfn(dev, mask) < max_dma_pfn)
 		return 0;
-	}
-
 	return 1;
 }
 
-static u64 get_coherent_dma_mask(struct device *dev)
-{
-	u64 mask = (u64)DMA_BIT_MASK(32);
-
-	if (dev) {
-		mask = dev->coherent_dma_mask;
-
-		/*
-		 * Sanity check the DMA mask - it must be non-zero, and
-		 * must be able to be satisfied by a DMA allocation.
-		 */
-		if (mask == 0) {
-			dev_warn(dev, "coherent DMA mask is unset\n");
-			return 0;
-		}
-
-		if (!__dma_supported(dev, mask, true))
-			return 0;
-	}
-
-	return mask;
-}
-
 static void __dma_clear_buffer(struct page *page, size_t size, int coherent_flag)
 {
 	/*
@@ -688,7 +658,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 			 gfp_t gfp, pgprot_t prot, bool is_coherent,
 			 unsigned long attrs, const void *caller)
 {
-	u64 mask = get_coherent_dma_mask(dev);
+	u64 mask = dev->coherent_dma_mask;
 	struct page *page = NULL;
 	void *addr;
 	bool allowblock, cma;
@@ -712,9 +682,6 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 	}
 #endif
 
-	if (!mask)
-		return NULL;
-
 	buf = kzalloc(sizeof(*buf),
 		      gfp & ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM));
 	if (!buf)
@@ -1095,7 +1062,7 @@ void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
  */
 int arm_dma_supported(struct device *dev, u64 mask)
 {
-	return __dma_supported(dev, mask, false);
+	return __dma_supported(dev, mask);
 }
 
 static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
-- 
2.24.1

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[PATCH 2/3] ARM/dma-mapping: take the bus limit into account in __dma_alloc

[Christoph Hellwig]

The DMA coherent allocator needs to take bus limits into account for
picking the zone that the memory is allocated from.

Reported-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Roger Quadros <rogerq@ti.com>
---
 arch/arm/mm/dma-mapping.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 72ddc3d0f5eb..87aba505554a 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -658,7 +658,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 			 gfp_t gfp, pgprot_t prot, bool is_coherent,
 			 unsigned long attrs, const void *caller)
 {
-	u64 mask = dev->coherent_dma_mask;
+	u64 mask = min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
 	struct page *page = NULL;
 	void *addr;
 	bool allowblock, cma;
-- 
2.24.1

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[PATCH 3/3] ARM/dma-mapping: merge __dma_supported into arm_dma_supported

[Christoph Hellwig]

Merge __dma_supported into its only caller, and move the resulting
function so that it doesn't need a forward declaration.  Also mark
it static as there are no callers outside of dma-mapping.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/include/asm/dma-iommu.h |  2 --
 arch/arm/mm/dma-mapping.c        | 41 +++++++++++++-------------------
 2 files changed, 17 insertions(+), 26 deletions(-)

diff --git a/arch/arm/include/asm/dma-iommu.h b/arch/arm/include/asm/dma-iommu.h
index 772f48ef84b7..86405cc81385 100644
--- a/arch/arm/include/asm/dma-iommu.h
+++ b/arch/arm/include/asm/dma-iommu.h
@@ -33,7 +33,5 @@ int arm_iommu_attach_device(struct device *dev,
 					struct dma_iommu_mapping *mapping);
 void arm_iommu_detach_device(struct device *dev);
 
-int arm_dma_supported(struct device *dev, u64 mask);
-
 #endif /* __KERNEL__ */
 #endif
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 87aba505554a..8a8949174b1c 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -179,6 +179,23 @@ static void arm_dma_sync_single_for_device(struct device *dev,
 	__dma_page_cpu_to_dev(page, offset, size, dir);
 }
 
+/*
+ * Return whether the given device DMA address mask can be supported
+ * properly.  For example, if your device can only drive the low 24-bits
+ * during bus mastering, then you would pass 0x00ffffff as the mask
+ * to this function.
+ */
+static int arm_dma_supported(struct device *dev, u64 mask)
+{
+	unsigned long max_dma_pfn = min(max_pfn - 1, arm_dma_pfn_limit);
+
+	/*
+	 * Translate the device's DMA mask to a PFN limit.  This
+	 * PFN number includes the page which we can DMA to.
+	 */
+	return dma_to_pfn(dev, mask) >= max_dma_pfn;
+}
+
 const struct dma_map_ops arm_dma_ops = {
 	.alloc			= arm_dma_alloc,
 	.free			= arm_dma_free,
@@ -219,19 +236,6 @@ const struct dma_map_ops arm_coherent_dma_ops = {
 };
 EXPORT_SYMBOL(arm_coherent_dma_ops);
 
-static int __dma_supported(struct device *dev, u64 mask)
-{
-	unsigned long max_dma_pfn = min(max_pfn - 1, arm_dma_pfn_limit);
-
-	/*
-	 * Translate the device's DMA mask to a PFN limit.  This
-	 * PFN number includes the page which we can DMA to.
-	 */
-	if (dma_to_pfn(dev, mask) < max_dma_pfn)
-		return 0;
-	return 1;
-}
-
 static void __dma_clear_buffer(struct page *page, size_t size, int coherent_flag)
 {
 	/*
@@ -1054,17 +1058,6 @@ void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 					    dir);
 }
 
-/*
- * Return whether the given device DMA address mask can be supported
- * properly.  For example, if your device can only drive the low 24-bits
- * during bus mastering, then you would pass 0x00ffffff as the mask
- * to this function.
- */
-int arm_dma_supported(struct device *dev, u64 mask)
-{
-	return __dma_supported(dev, mask);
-}
-
 static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
 {
 	/*
-- 
2.24.1

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Re: take the bus_dma_limit into account on arm

[Roger Quadros via iommu]

Hi Russell,

On 18/02/2020 20:41, Christoph Hellwig wrote:
> Hi Russell,
> 
> this series fixes the arm dma coherent allocator to take the bus dma
> mask into account, similar to what other architectures do.  Without
> this devices that support 64-bit mask, but are limited by the
> interconnect won't work properly.
> 

Can we please have this series marked for -stable? Thanks.

-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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Re: take the bus_dma_limit into account on arm

[Christoph Hellwig]

As there seems no movement I've added it to my for-next branch so that
it at least gets some linux-next exposure.

But it really needs a few reviews.
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