1 files changed, 15 insertions, 6 deletions

diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index 8321a3997c95..07bca4970e50 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -79,6 +79,7 @@
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/slab.h>
+#include <linux/delay.h>
 #include <linux/dmapool.h>
 #include <linux/dmaengine.h>
 #include <linux/amba/bus.h>
@@ -235,16 +236,19 @@ static void pl08x_start_txd(struct pl08x_dma_chan *plchan,
 }
 
 /*
- * Overall DMAC remains enabled always.
+ * Pause the channel by setting the HALT bit.
  *
- * Disabling individual channels could lose data.
+ * For M->P transfers, pause the DMAC first and then stop the peripheral -
+ * the FIFO can only drain if the peripheral is still requesting data.
+ * (note: this can still timeout if the DMAC FIFO never drains of data.)
  *
- * Disable the peripheral DMA after disabling the DMAC in order to allow
- * the DMAC FIFO to drain, and hence allow the channel to show inactive
+ * For P->M transfers, disable the peripheral first to stop it filling
+ * the DMAC FIFO, and then pause the DMAC.
  */
 static void pl08x_pause_phy_chan(struct pl08x_phy_chan *ch)
 {
         u32 val;
+        int timeout;
 
         /* Set the HALT bit and wait for the FIFO to drain */
         val = readl(ch->base + PL080_CH_CONFIG);
@@ -252,8 +256,13 @@ static void pl08x_pause_phy_chan(struct pl08x_phy_chan *ch)
         writel(val, ch->base + PL080_CH_CONFIG);
 
         /* Wait for channel inactive */
-        while (pl08x_phy_channel_busy(ch))
-                cpu_relax();
+        for (timeout = 1000; timeout; timeout--) {
+                if (!pl08x_phy_channel_busy(ch))
+                        break;
+                udelay(1);
+        }
+        if (pl08x_phy_channel_busy(ch))
+                pr_err("pl08x: channel%u timeout waiting for pause\n", ch->id);
 }
 
 static void pl08x_resume_phy_chan(struct pl08x_phy_chan *ch)