Re: [RFC 03/13] v4l: vb2-dma-contig: let mmap method to use dma_mmap_coherent call

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomasz,

Thanks for the patch.

On Tuesday 10 April 2012 15:10:37 Tomasz Stanislawski wrote:
> From: Marek Szyprowski <m.szyprowski@samsung.com>
> 
> Let mmap method to use dma_mmap_coherent call.  This patch depends on DMA
> mapping redesign patches because the usage of dma_mmap_coherent breaks
> dma-contig allocator for architectures other than ARM and AVR.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>  drivers/media/video/videobuf2-dma-contig.c |   28 +++++++++++++++++++++++--
>  1 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/video/videobuf2-dma-contig.c
> b/drivers/media/video/videobuf2-dma-contig.c index 6329483..f4df9e2 100644
> --- a/drivers/media/video/videobuf2-dma-contig.c
> +++ b/drivers/media/video/videobuf2-dma-contig.c
> @@ -224,14 +224,38 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned
> long size) static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct
> *vma) {
>  	struct vb2_dc_buf *buf = buf_priv;
> +	int ret;
> 
>  	if (!buf) {
>  		printk(KERN_ERR "No buffer to map\n");
>  		return -EINVAL;
>  	}
> 
> -	return vb2_mmap_pfn_range(vma, buf->dma_addr, buf->size,
> -				  &vb2_common_vm_ops, &buf->handler);

This was the only vb2_mmap_pfn_range() if I'm not mistaken. Should the 
function be removed ?

> +	/*
> +	 * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
> +	 * map whole buffer
> +	 */
> +	vma->vm_pgoff = 0;

Is it safe to set vma->vm_pgoff to 0 here behind memory core's back ?

> +	ret = dma_mmap_coherent(buf->dev, vma, buf->vaddr,
> +		buf->dma_addr, buf->size);
> +
> +	if (ret) {
> +		printk(KERN_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);
> +
> +	printk(KERN_DEBUG "%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
> +		__func__, (unsigned long)buf->dma_addr, vma->vm_start,
> +		buf->size);
> +
> +	return 0;
>  }
> 
>  /*********************************************/
-- 
Regards,

Laurent Pinchart