linux-kernel - [RFC PATCH] dma: coherent: respect to device 'dma-coherent' property

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Date:   Fri, 14 Apr 2023 16:03:07 +0800
From:   Zhiqiang Hou <Zhiqiang.Hou@....com>
To:     iommu@...ts.linux.dev, linux-kernel@...r.kernel.org, hch@....de,
        m.szyprowski@...sung.com, robin.murphy@....com
Cc:     Hou Zhiqiang <Zhiqiang.Hou@....com>
Subject: [RFC PATCH] dma: coherent: respect to device 'dma-coherent' property

From: Hou Zhiqiang <Zhiqiang.Hou@....com>

Currently, the coherent DMA memory is always mapped as writecombine
and uncached, ignored the 'dma-coherent' property in device node,
this patch is to map the memory as writeback and cached when the
device has 'dma-coherent' property.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>
---
 kernel/dma/coherent.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index c21abc77c53e..f15ba6c6358e 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -36,7 +36,8 @@ static inline dma_addr_t dma_get_device_base(struct device *dev,
 }
 
 static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
-		dma_addr_t device_addr, size_t size, bool use_dma_pfn_offset)
+		dma_addr_t device_addr, size_t size, bool use_dma_pfn_offset,
+		bool cacheable)
 {
 	struct dma_coherent_mem *dma_mem;
 	int pages = size >> PAGE_SHIFT;
@@ -45,7 +46,8 @@ static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
 	if (!size)
 		return ERR_PTR(-EINVAL);
 
-	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
+	mem_base = memremap(phys_addr, size, cacheable ? MEMREMAP_WB :
+			    MEMREMAP_WC);
 	if (!mem_base)
 		return ERR_PTR(-EINVAL);
 
@@ -119,8 +121,10 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 {
 	struct dma_coherent_mem *mem;
 	int ret;
+	bool cacheable = dev_is_dma_coherent(dev);
 
-	mem = dma_init_coherent_memory(phys_addr, device_addr, size, false);
+	mem = dma_init_coherent_memory(phys_addr, device_addr, size, false,
+				       cacheable);
 	if (IS_ERR(mem))
 		return PTR_ERR(mem);
 
@@ -310,7 +314,7 @@ int dma_init_global_coherent(phys_addr_t phys_addr, size_t size)
 {
 	struct dma_coherent_mem *mem;
 
-	mem = dma_init_coherent_memory(phys_addr, phys_addr, size, true);
+	mem = dma_init_coherent_memory(phys_addr, phys_addr, size, true, false);
 	if (IS_ERR(mem))
 		return PTR_ERR(mem);
 	dma_coherent_default_memory = mem;
@@ -335,9 +339,10 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 {
 	if (!rmem->priv) {
 		struct dma_coherent_mem *mem;
+		bool cacheable = dev_is_dma_coherent(dev);
 
 		mem = dma_init_coherent_memory(rmem->base, rmem->base,
-					       rmem->size, true);
+					       rmem->size, true, cacheable);
 		if (IS_ERR(mem))
 			return PTR_ERR(mem);
 		rmem->priv = mem;
-- 
2.17.1