[IOAT]: ioatdma needs to to play nice in a multi-dma-client world

Now that the DMA engine has a multi-client interface, fix the ioatdma
driver to play along.  At the same time, remove a couple of unnecessary
reads and writes.

Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
index 2d1f17865b64a933f8a9901b899952fe0018706c..41b18c5a31412e13839b66be977eae92725dbb80 100644 (file)
--- a/drivers/dma/ioatdma.c
+++ b/drivers/dma/ioatdma.c
@@ -191,17 +191,12 @@ static int ioat_dma_alloc_chan_resources(struct dma_chan *chan)
        int i;
        LIST_HEAD(tmp_list);
 
-       /*
-        * In-use bit automatically set by reading chanctrl
-        * If 0, we got it, if 1, someone else did
-        */
-       chanctrl = readw(ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
-       if (chanctrl & IOAT_CHANCTRL_CHANNEL_IN_USE)
-               return -EBUSY;
+       /* have we already been set up? */
+       if (!list_empty(&ioat_chan->free_desc))
+               return INITIAL_IOAT_DESC_COUNT;
 
         /* Setup register to interrupt and write completion status on error */
-       chanctrl = IOAT_CHANCTRL_CHANNEL_IN_USE |
-               IOAT_CHANCTRL_ERR_INT_EN |
+       chanctrl = IOAT_CHANCTRL_ERR_INT_EN |
                IOAT_CHANCTRL_ANY_ERR_ABORT_EN |
                IOAT_CHANCTRL_ERR_COMPLETION_EN;
         writew(chanctrl, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
@@ -282,11 +277,6 @@ static void ioat_dma_free_chan_resources(struct dma_chan *chan)
                        in_use_descs - 1);
 
        ioat_chan->last_completion = ioat_chan->completion_addr = 0;
-
-       /* Tell hw the chan is free */
-       chanctrl = readw(ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
-       chanctrl &= ~IOAT_CHANCTRL_CHANNEL_IN_USE;
-       writew(chanctrl, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
 }
 
 static struct dma_async_tx_descriptor *