From 8a6a547fe1b13fe3e523b3f076f8295dd03a7c41 Mon Sep 17 00:00:00 2001 From: Fancy Fang Date: Thu, 9 Oct 2014 23:21:22 -0300 Subject: [PATCH] [media] videobuf-dma-contig: set vm_pgoff to be zero to pass the sanity check in vm_iomap_memory() When user requests V4L2_MEMORY_MMAP type buffers, the videobuf-core will assign the corresponding offset to the 'boff' field of the videobuf_buffer for each requested buffer sequentially. Later, user may call mmap() to map one or all of the buffers with the 'offset' parameter which is equal to its 'boff' value. Obviously, the 'offset' value is only used to find the matched buffer instead of to be the real offset from the buffer's physical start address as used by vm_iomap_memory(). So, in some case that if the offset is not zero, vm_iomap_memory() will fail. Signed-off-by: Fancy Fang Reviewed-by: Marek Szyprowski Reviewed-by: Hans Verkuil Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- drivers/media/v4l2-core/videobuf-dma-contig.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/media/v4l2-core/videobuf-dma-contig.c index bf80f0f7dfb8..e02353e340dd 100644 --- a/drivers/media/v4l2-core/videobuf-dma-contig.c +++ b/drivers/media/v4l2-core/videobuf-dma-contig.c @@ -305,6 +305,15 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q, /* 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(). + */ + vma->vm_pgoff = 0; + retval = vm_iomap_memory(vma, mem->dma_handle, size); if (retval) { dev_err(q->dev, "mmap: remap failed with error %d. ", -- 2.20.1