drm/prime: fix extracting of the DMA addresses from a scatterlist

	unsigned count;

	struct scatterlist *sg;

	struct page *page;

	u32 len, index;

	u32 page_len, page_index;

	dma_addr_t addr;

	u32 dma_len, dma_index;

	index = 0;

	/*

	 * Scatterlist elements contains both pages and DMA addresses, but

	 * one shoud not assume 1:1 relation between them. The sg->length is

	 * the size of the physical memory chunk described by the sg->page,

	 * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk

	 * described by the sg_dma_address(sg).

	 */

	page_index = 0;

	dma_index = 0;

	for_each_sg(sgt->sgl, sg, sgt->nents, count) {

		len = sg_dma_len(sg);

		page_len = sg->length;

		page = sg_page(sg);

		dma_len = sg_dma_len(sg);

		addr = sg_dma_address(sg);

		while (len > 0) {

			if (WARN_ON(index >= max_entries))

		while (pages && page_len > 0) {

			if (WARN_ON(page_index >= max_entries))

				return -1;

			if (pages)

				pages[index] = page;

			if (addrs)

				addrs[index] = addr;

			pages[page_index] = page;

			page++;

			page_len -= PAGE_SIZE;

			page_index++;

		}

		while (addrs && dma_len > 0) {

			if (WARN_ON(dma_index >= max_entries))

				return -1;

			addrs[dma_index] = addr;

			addr += PAGE_SIZE;

			len -= PAGE_SIZE;

			index++;

			dma_len -= PAGE_SIZE;

			dma_index++;

		}

	}

	return 0;