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>

diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index f7f571e..ec7eddf 100644 (file)
--- 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 02232ca..af3a039 100644 (file)
--- 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