dmaengine: PL08x: re-jig the starting of txds

Rather than code the de-queue of the txd several times, move that into
the start_txd function.  Rename this to better illustrate what it's
now doing, and call this function when starting a delayed memcpy().

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 17 insertions, 20 deletions

diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index 88661fa4542c..c278d23adee7 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -354,20 +354,25 @@ static int pl08x_phy_channel_busy(struct pl08x_phy_chan *ch)
  * been set when the LLIs were constructed.  Poke them into the hardware
  * and start the transfer.
  */
-static void pl08x_start_txd(struct pl08x_dma_chan *plchan,
-        struct pl08x_txd *txd)
+static void pl08x_start_next_txd(struct pl08x_dma_chan *plchan)
 {
         struct pl08x_driver_data *pl08x = plchan->host;
         struct pl08x_phy_chan *phychan = plchan->phychan;
-        struct pl08x_lli *lli = &txd->llis_va[0];
+        struct pl08x_lli *lli;
+        struct pl08x_txd *txd;
         u32 val;
 
+        txd = list_first_entry(&plchan->pend_list, struct pl08x_txd, node);
+        list_del(&txd->node);
+
         plchan->at = txd;
 
         /* Wait for channel inactive */
         while (pl08x_phy_channel_busy(phychan))
                 cpu_relax();
 
+        lli = &txd->llis_va[0];
+
         dev_vdbg(&pl08x->adev->dev,
                 "WRITE channel %d: csrc=0x%08x, cdst=0x%08x, "
                 "clli=0x%08x, cctl=0x%08x, ccfg=0x%08x\n",
@@ -1272,15 +1277,8 @@ static void pl08x_issue_pending(struct dma_chan *chan)
 
         /* Take the first element in the queue and execute it */
         if (!list_empty(&plchan->pend_list)) {
-                struct pl08x_txd *next;
-
-                next = list_first_entry(&plchan->pend_list,
-                                        struct pl08x_txd,
-                                        node);
-                list_del(&next->node);
                 plchan->state = PL08X_CHAN_RUNNING;
-
-                pl08x_start_txd(plchan, next);
+                pl08x_start_next_txd(plchan);
         }
 
         spin_unlock_irqrestore(&plchan->lock, flags);
@@ -1661,14 +1659,7 @@ static void pl08x_tasklet(unsigned long data)
 
         /* If a new descriptor is queued, set it up plchan->at is NULL here */
         if (!list_empty(&plchan->pend_list)) {
-                struct pl08x_txd *next;
-
-                next = list_first_entry(&plchan->pend_list,
-                                        struct pl08x_txd,
-                                        node);
-                list_del(&next->node);
-
-                pl08x_start_txd(plchan, next);
+                pl08x_start_next_txd(plchan);
         } else if (plchan->phychan_hold) {
                 /*
                  * This channel is still in use - we have a new txd being
@@ -1700,7 +1691,13 @@ static void pl08x_tasklet(unsigned long data)
                                 BUG_ON(ret);
                                 waiting->phychan_hold--;
                                 waiting->state = PL08X_CHAN_RUNNING;
-                                pl08x_issue_pending(&waiting->chan);
+                                /*
+                                 * Eww.  We know this isn't going to deadlock
+                                 * but lockdep probably doens't.
+                                 */
+                                spin_lock(&waiting->lock);
+                                pl08x_start_next_txd(waiting);
+                                spin_unlock(&waiting->lock);
                                 break;
                         }
                 }