[PATCH 01/16] media: videobuf-dma-contig: use dma_mmap_coherent

Christoph Hellwig hch at lst.de
Fri Jun 14 13:47:11 UTC 2019


dma_alloc_coherent does not return a physical address, but a DMA
address, which might be remapped or have an offset.  Passing this
DMA address to vm_iomap_memory is completely bogus.  Use the proper
dma_mmap_coherent helper instead, and stop passing __GFP_COMP
to dma_alloc_coherent, as the memory management inside the DMA
allocator is hidden from the callers.

Fixes: a8f3c203e19b ("[media] videobuf-dma-contig: add cache support")
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/media/v4l2-core/videobuf-dma-contig.c | 23 +++++++------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/media/v4l2-core/videobuf-dma-contig.c
index e1bf50df4c70..a5942ea38f1f 100644
--- a/drivers/media/v4l2-core/videobuf-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
@@ -39,11 +39,11 @@ struct videobuf_dma_contig_memory {
 
 static int __videobuf_dc_alloc(struct device *dev,
 			       struct videobuf_dma_contig_memory *mem,
-			       unsigned long size, gfp_t flags)
+			       unsigned long size)
 {
 	mem->size = size;
-	mem->vaddr = dma_alloc_coherent(dev, mem->size,
-					&mem->dma_handle, flags);
+	mem->vaddr = dma_alloc_coherent(dev, mem->size, &mem->dma_handle,
+			GFP_KERNEL);
 
 	if (!mem->vaddr) {
 		dev_err(dev, "memory alloc size %ld failed\n", mem->size);
@@ -260,8 +260,7 @@ static int __videobuf_iolock(struct videobuf_queue *q,
 			return videobuf_dma_contig_user_get(mem, vb);
 
 		/* allocate memory for the read() method */
-		if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size),
-					GFP_KERNEL))
+		if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size)))
 			return -ENOMEM;
 		break;
 	case V4L2_MEMORY_OVERLAY:
@@ -280,7 +279,6 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 	struct videobuf_dma_contig_memory *mem;
 	struct videobuf_mapping *map;
 	int retval;
-	unsigned long size;
 
 	dev_dbg(q->dev, "%s\n", __func__);
 
@@ -298,23 +296,18 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 	BUG_ON(!mem);
 	MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 
-	if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(buf->bsize),
-				GFP_KERNEL | __GFP_COMP))
+	if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(buf->bsize)))
 		goto error;
 
-	/* Try to remap memory */
-	size = vma->vm_end - vma->vm_start;
-	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-
 	/* the "vm_pgoff" is just used in v4l2 to find the
 	 * corresponding buffer data structure which is allocated
 	 * earlier and it does not mean the offset from the physical
 	 * buffer start address as usual. So set it to 0 to pass
-	 * the sanity check in vm_iomap_memory().
+	 * the sanity check in dma_mmap_coherent().
 	 */
 	vma->vm_pgoff = 0;
-
-	retval = vm_iomap_memory(vma, mem->dma_handle, size);
+	retval = dma_mmap_coherent(q->dev, vma, mem->vaddr, mem->dma_handle,
+			vma->vm_end - vma->vm_start);
 	if (retval) {
 		dev_err(q->dev, "mmap: remap failed with error %d. ",
 			retval);
-- 
2.20.1



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