Patch "media: videobuf-dma-contig: use dma_mmap_coherent" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    media: videobuf-dma-contig: use dma_mmap_coherent

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     media-videobuf-dma-contig-use-dma_mmap_coherent.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit eadfe0a64bf71d3ab487dba28acd59a2101753be
Author: Christoph Hellwig <hch@xxxxxx>
Date:   Wed Dec 18 11:39:07 2019 +0100

    media: videobuf-dma-contig: use dma_mmap_coherent
    
    [ Upstream commit b3dc3f8e49577840dc8ac8a365c5b3da4edb10b8 ]
    
    dma_alloc_coherent does not return a physical address, but a DMA address,
    which might be remapped or have an offset.  Passing the DMA address to
    vm_iomap_memory is thus broken.
    
    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 and does not require it.
    
    With this the gfp_t argument to __videobuf_dc_alloc can be removed and
    hard coded to GFP_KERNEL.
    
    Fixes: a8f3c203e19b ("[media] videobuf-dma-contig: add cache support")
    Signed-off-by: Christoph Hellwig <hch@xxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/media/v4l2-core/videobuf-dma-contig.c
index aeb2f497c683..6a6cd046cefb 100644
--- a/drivers/media/v4l2-core/videobuf-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
@@ -36,12 +36,11 @@ 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);
 		return -ENOMEM;
@@ -258,8 +257,7 @@ 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:
@@ -295,22 +293,18 @@ 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 */
-	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, mem->size);
+	retval = dma_mmap_coherent(q->dev, vma, mem->vaddr, mem->dma_handle,
+				   mem->size);
 	if (retval) {
 		dev_err(q->dev, "mmap: remap failed with error %d. ",
 			retval);