RE: [PATCH v2 3/4] media: videobuf2-dma-contig: use dma_mmap_coherent if available

[Marek Szyprowski]

Hello,

On Thursday, July 26, 2012 1:13 PM Hideki EIRAKU wrote:

 Previously the vb2_dma_contig_mmap() function was using a dma_addr_t as a
 physical address.  The two addressses are not necessarily the same.
 For example, when using the IOMMU funtion on certain platforms, dma_addr_t
 addresses are not directly mappable physical address.
 dma_mmap_coherent() maps the address correctly.
 It is available on ARM platforms.
 
 Signed-off-by: Hideki EIRAKU h...@igel.co.jp
 ---
  drivers/media/video/videobuf2-dma-contig.c |   18 ++
  1 files changed, 18 insertions(+), 0 deletions(-)
 
 diff --git a/drivers/media/video/videobuf2-dma-contig.c 
 b/drivers/media/video/videobuf2-dma-
 contig.c
 index 4b71326..4dc85ab 100644
 --- a/drivers/media/video/videobuf2-dma-contig.c
 +++ b/drivers/media/video/videobuf2-dma-contig.c
 @@ -101,14 +101,32 @@ static unsigned int vb2_dma_contig_num_users(void 
 *buf_priv)
  static int vb2_dma_contig_mmap(void *buf_priv, struct vm_area_struct *vma)
  {
   struct vb2_dc_buf *buf = buf_priv;
 +#ifdef ARCH_HAS_DMA_MMAP_COHERENT
 + int ret;
 +#endif
 
   if (!buf) {
   printk(KERN_ERR No buffer to map\n);
   return -EINVAL;
   }
 
 +#ifdef ARCH_HAS_DMA_MMAP_COHERENT
 + vma-vm_page_prot = pgprot_noncached(vma-vm_page_prot);

The above line is not needed. It is up to dma_mmap_coherent() / 
dma_mmap_attrs() to set page
protection bits which match requested type of dma buffer mapping.

 + ret = dma_mmap_coherent(buf-conf-dev, vma, buf-vaddr, buf-dma_addr,
 + buf-size);
 + if (ret) {
 + pr_err(Remapping memory failed, error: %d\n, ret);
 + return ret;
 + }
 + vma-vm_flags |= VM_DONTEXPAND | VM_RESERVED;
 + vma-vm_private_data = buf-handler;
 + vma-vm_ops = vb2_common_vm_ops;
 + vma-vm_ops-open(vma);
 + return 0;
 +#else
   return vb2_mmap_pfn_range(vma, buf-dma_addr, buf-size,
 vb2_common_vm_ops, buf-handler);
 +#endif
  }
 
  static void *vb2_dma_contig_get_userptr(void *alloc_ctx, unsigned long vaddr,

Best regards
-- 
Marek Szyprowski
Samsung Poland RD Center


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[PATCH v2 3/4] media: videobuf2-dma-contig: use dma_mmap_coherent if available

[Hideki EIRAKU]

Previously the vb2_dma_contig_mmap() function was using a dma_addr_t as a
physical address.  The two addressses are not necessarily the same.
For example, when using the IOMMU funtion on certain platforms, dma_addr_t
addresses are not directly mappable physical address.
dma_mmap_coherent() maps the address correctly.
It is available on ARM platforms.

Signed-off-by: Hideki EIRAKU h...@igel.co.jp
---
 drivers/media/video/videobuf2-dma-contig.c |   18 ++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/videobuf2-dma-contig.c 
b/drivers/media/video/videobuf2-dma-contig.c
index 4b71326..4dc85ab 100644
--- a/drivers/media/video/videobuf2-dma-contig.c
+++ b/drivers/media/video/videobuf2-dma-contig.c
@@ -101,14 +101,32 @@ static unsigned int vb2_dma_contig_num_users(void 
*buf_priv)
 static int vb2_dma_contig_mmap(void *buf_priv, struct vm_area_struct *vma)
 {
struct vb2_dc_buf *buf = buf_priv;
+#ifdef ARCH_HAS_DMA_MMAP_COHERENT
+   int ret;
+#endif
 
if (!buf) {
printk(KERN_ERR No buffer to map\n);
return -EINVAL;
}
 
+#ifdef ARCH_HAS_DMA_MMAP_COHERENT
+   vma-vm_page_prot = pgprot_noncached(vma-vm_page_prot);
+   ret = dma_mmap_coherent(buf-conf-dev, vma, buf-vaddr, buf-dma_addr,
+   buf-size);
+   if (ret) {
+   pr_err(Remapping memory failed, error: %d\n, ret);
+   return ret;
+   }
+   vma-vm_flags |= VM_DONTEXPAND | VM_RESERVED;
+   vma-vm_private_data = buf-handler;
+   vma-vm_ops = vb2_common_vm_ops;
+   vma-vm_ops-open(vma);
+   return 0;
+#else
return vb2_mmap_pfn_range(vma, buf-dma_addr, buf-size,
  vb2_common_vm_ops, buf-handler);
+#endif
 }
 
 static void *vb2_dma_contig_get_userptr(void *alloc_ctx, unsigned long vaddr,
-- 
1.7.0.4

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