From mboxrd@z Thu Jan 1 00:00:00 1970 From: vinod.koul@intel.com (Vinod Koul) Date: Fri, 9 Oct 2015 17:12:09 +0100 Subject: [PATCH v2] dmaengine: xgene-dma: Disable memcpy operation due to performance drop In-Reply-To: <1444295217-3099-1-git-send-email-rsahu@apm.com> References: <1444295217-3099-1-git-send-email-rsahu@apm.com> Message-ID: <20151009161208.GJ3609@vkoul-mobl.iind.intel.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Oct 08, 2015 at 02:36:57PM +0530, Rameshwar Prasad Sahu wrote: > 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 > --- > 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); This will not work. Still clients can invoke memcpy operation. You need to remove the callback -- ~Vinod