[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>

1 files changed, 4 insertions, 14 deletions

diff --git a/drivers/dma/ioatdma.c b/drivers/dma/ioatdma.c
index 2d1f17865b64..41b18c5a3141 100644
--- 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 *