ioat3: enable dca for completion writes
Dan Williams [Wed, 9 Sep 2009 00:42:57 +0000 (17:42 -0700)]
Tag completion writes for direct cache access to reduce the latency of
checking for descriptor completions.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/ioat/dma_v3.c
drivers/dma/ioat/registers.h

index 22af78e..0913d11 100644 (file)
@@ -167,7 +167,8 @@ static void ioat3_cleanup_tasklet(unsigned long data)
        struct ioat2_dma_chan *ioat = (void *) data;
 
        ioat3_cleanup(ioat);
-       writew(IOAT_CHANCTRL_RUN, ioat->base.reg_base + IOAT_CHANCTRL_OFFSET);
+       writew(IOAT_CHANCTRL_RUN | IOAT3_CHANCTRL_COMPL_DCA_EN,
+              ioat->base.reg_base + IOAT_CHANCTRL_OFFSET);
 }
 
 static void ioat3_restart_channel(struct ioat2_dma_chan *ioat)
index 85d04b8..97d26ea 100644 (file)
@@ -84,6 +84,7 @@
 /* DMA Channel Registers */
 #define IOAT_CHANCTRL_OFFSET                   0x00    /* 16-bit Channel Control Register */
 #define IOAT_CHANCTRL_CHANNEL_PRIORITY_MASK    0xF000
+#define IOAT3_CHANCTRL_COMPL_DCA_EN            0x0200
 #define IOAT_CHANCTRL_CHANNEL_IN_USE           0x0100
 #define IOAT_CHANCTRL_DESCRIPTOR_ADDR_SNOOP_CONTROL    0x0020
 #define IOAT_CHANCTRL_ERR_INT_EN               0x0010