dmaengine: omap-dma: Start DMA without delay for cyclic channels

cyclic DMA is only used by audio which needs DMA to be started without a
delay.
If the DMA for audio is started using the tasklet we experience random
channel switch (to be more precise: channel shift).

Reported-by: Peter Meerwald <pmeerw@pmeerw.net>
CC: stable@vger.kernel.org  # v3.7+
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 14 insertions, 6 deletions

diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
index c4b4fd2acc42..08b43bf37158 100644
--- a/drivers/dma/omap-dma.c
+++ b/drivers/dma/omap-dma.c
@@ -276,12 +276,20 @@ static void omap_dma_issue_pending(struct dma_chan *chan)
 
         spin_lock_irqsave(&c->vc.lock, flags);
         if (vchan_issue_pending(&c->vc) && !c->desc) {
-                struct omap_dmadev *d = to_omap_dma_dev(chan->device);
-                spin_lock(&d->lock);
-                if (list_empty(&c->node))
-                        list_add_tail(&c->node, &d->pending);
-                spin_unlock(&d->lock);
-                tasklet_schedule(&d->task);
+                /*
+                 * c->cyclic is used only by audio and in this case the DMA need
+                 * to be started without delay.
+                 */
+                if (!c->cyclic) {
+                        struct omap_dmadev *d = to_omap_dma_dev(chan->device);
+                        spin_lock(&d->lock);
+                        if (list_empty(&c->node))
+                                list_add_tail(&c->node, &d->pending);
+                        spin_unlock(&d->lock);
+                        tasklet_schedule(&d->task);
+                } else {
+                        omap_dma_start_desc(c);
+                }
         }
         spin_unlock_irqrestore(&c->vc.lock, flags);
 }