linux-kernel - [PATCH v2] dmaengine: xgene-dma: Disable memcpy operation due to performance drop

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Message-Id: <1444295217-3099-1-git-send-email-rsahu@apm.com>
Date:	Thu,  8 Oct 2015 14:36:57 +0530
From:	Rameshwar Prasad Sahu <rsahu@....com>
To:	vinod.koul@...el.com, dan.j.williams@...el.com
Cc:	dmaengine@...r.kernel.org, arnd@...db.de,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, jcm@...hat.com,
	patches@....com, Rameshwar Prasad Sahu <rsahu@....com>
Subject: [PATCH v2] dmaengine: xgene-dma: Disable memcpy operation due to performance drop

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@....com>
---
 drivers/dma/xgene-dma.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/dma/xgene-dma.c b/drivers/dma/xgene-dma.c
index 8d57b1b..cd38022 100644
--- a/drivers/dma/xgene-dma.c
+++ b/drivers/dma/xgene-dma.c
@@ -1707,7 +1707,6 @@ static void xgene_dma_set_caps(struct xgene_dma_chan *chan,
 	dma_cap_zero(dma_dev->cap_mask);

 	/* Set DMA device capability */
-	dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
 	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

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