[PATCH] dmaengine: xgene-dma: Disable memcpy operation due to performance drop

[Rameshwar Prasad Sahu]

The DMA engine supports memory copy, RAID5 XOR, RAID6 PQ, and other
computations. But the bandwidth of the entire DMA engine is shared
among all channels. This patch re-configures operations availability
such that one can achieve maximum performance for XOR and PQ
computation by removing the memory offload operations.

Signed-off-by: Rameshwar Prasad Sahu <rsahu at apm.com>
---
 drivers/dma/xgene-dma.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/dma/xgene-dma.c b/drivers/dma/xgene-dma.c
index 8d57b1b..2998fcb 100644
--- a/drivers/dma/xgene-dma.c
+++ b/drivers/dma/xgene-dma.c
@@ -154,6 +154,7 @@
 #define XGENE_DMA_MAX_XOR_SRC		5
 #define XGENE_DMA_16K_BUFFER_LEN_CODE	0x0
 #define XGENE_DMA_INVALID_LEN_CODE	0x7800000000000000ULL
+#undef XGENE_DMA_MEMCPY_ENABLE

 /* X-Gene DMA descriptor error codes */
 #define ERR_DESC_AXI			0x01
@@ -1707,7 +1708,9 @@ static void xgene_dma_set_caps(struct xgene_dma_chan *chan,
 	dma_cap_zero(dma_dev->cap_mask);

 	/* Set DMA device capability */
+#ifdef XGENE_DMA_MEMCPY_ENABLE
 	dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
+#endif
 	dma_cap_set(DMA_SG, dma_dev->cap_mask);

 	/* Basically here, the X-Gene SoC DMA engine channel 0 supports XOR
--
1.8.2.1