staging: comedi: mite: tidy up mite_init_ring_descriptors() (3303410d) · Commits · 戴 / test

drivers/staging/comedi/drivers/mite.c

+10 −12

Original line number	Diff line number	Diff line
		@@ -516,6 +516,7 @@ int mite_init_ring_descriptors(struct mite_ring *ring,
		unsigned int nbytes)
		{
		struct comedi_async *async = s->async;
		struct mite_dma_desc *desc = NULL;
		unsigned int n_full_links = nbytes >> PAGE_SHIFT;
		unsigned int remainder = nbytes % PAGE_SIZE;
		int i;
		@@ -531,26 +532,23 @@ int mite_init_ring_descriptors(struct mite_ring *ring,

		/* We set the descriptors for all full links. */
		for (i = 0; i < n_full_links; ++i) {
		ring->descs[i].count = cpu_to_le32(PAGE_SIZE);
		ring->descs[i].addr =
		cpu_to_le32(async->buf_map->page_list[i].dma_addr);
		ring->descs[i].next =
		cpu_to_le32(ring->dma_addr +
		(i + 1) * sizeof(struct mite_dma_desc));
		desc = &ring->descs[i];
		desc->count = cpu_to_le32(PAGE_SIZE);
		desc->addr = cpu_to_le32(async->buf_map->page_list[i].dma_addr);
		desc->next = cpu_to_le32(ring->dma_addr +
		(i + 1) * sizeof(*desc));
		}

		/* the last link is either a remainder or was a full link. */
		if (remainder > 0) {
		desc = &ring->descs[i];
		/* set the lesser count for the remainder link */
		ring->descs[i].count = cpu_to_le32(remainder);
		ring->descs[i].addr =
		cpu_to_le32(async->buf_map->page_list[i].dma_addr);
		/* increment i so that assignment below refs last link */
		++i;
		desc->count = cpu_to_le32(remainder);
		desc->addr = cpu_to_le32(async->buf_map->page_list[i].dma_addr);
		}

		/* Assign the last link->next to point back to the head of the list. */
		ring->descs[i - 1].next = cpu_to_le32(ring->dma_addr);
		desc->next = cpu_to_le32(ring->dma_addr);

		/*
		* barrier is meant to insure that all the writes to the dma descriptors

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