omap: dma: Support for prefetch in destination synchronizedtransfer

Omap DMA controller can prefetch data in advance in case of
destination synchronized data transfer. This may increase
performance when target HW block doesn't have fifo.
Data is waiting for transfer request in DMA fifo instead of read from memory.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

2 files changed, 8 insertions, 4 deletions

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index f7f571e7987e..ec7eddf9e525 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -290,7 +290,7 @@ void omap_set_dma_transfer_params(int lch, int data_type, int elem_count,
                 val = dma_read(CCR(lch));
 
                 /* DMA_SYNCHRO_CONTROL_UPPER depends on the channel number */
-                val &= ~((3 << 19) | 0x1f);
+                val &= ~((1 << 23) | (3 << 19) | 0x1f);
                 val |= (dma_trigger & ~0x1f) << 14;
                 val |= dma_trigger & 0x1f;
 
@@ -304,11 +304,14 @@ void omap_set_dma_transfer_params(int lch, int data_type, int elem_count,
                 else
                         val &= ~(1 << 18);
 
-                if (src_or_dst_synch)
+                if (src_or_dst_synch == OMAP_DMA_DST_SYNC_PREFETCH) {
+                        val &= ~(1 << 24);      /* dest synch */
+                        val |= (1 << 23);       /* Prefetch */
+                } else if (src_or_dst_synch) {
                         val |= 1 << 24;         /* source synch */
-                else
+                } else {
                         val &= ~(1 << 24);      /* dest synch */
-
+                }
                 dma_write(val, CCR(lch));
         }
 
diff --git a/arch/arm/plat-omap/include/plat/dma.h b/arch/arm/plat-omap/include/plat/dma.h
index 02232ca2c37f..af3a03941add 100644
--- a/arch/arm/plat-omap/include/plat/dma.h
+++ b/arch/arm/plat-omap/include/plat/dma.h
@@ -345,6 +345,7 @@
 #define OMAP_DMA_SYNC_BLOCK             0x02
 #define OMAP_DMA_SYNC_PACKET            0x03
 
+#define OMAP_DMA_DST_SYNC_PREFETCH      0x02
 #define OMAP_DMA_SRC_SYNC               0x01
 #define OMAP_DMA_DST_SYNC               0x00