From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Subject: [PATCH 3/4] mxs/spi: Decrement the DMA/PIO border Date: Tue, 4 Sep 2012 04:40:17 +0200 Message-ID: <1346726418-2856-4-git-send-email-marex@denx.de> References: <1346726418-2856-1-git-send-email-marex@denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Marek Vasut , Fabio Estevam , Shawn Guo , Mark Brown , Chris Ball , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Return-path: In-Reply-To: <1346726418-2856-1-git-send-email-marex-ynQEQJNshbs@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org This driver checks the length of transfer to be made and based on this information, either chooses to transfer data via DMA or PIO. Decrement this border further to gain better performace eg. during SPI flash writes. Empiric measurement shows that this gives extra 3kB/s write speed with a M25P80 flash clocked at 40MHz. Signed-off-by: Marek Vasut Cc: Chris Ball Cc: Fabio Estevam Cc: Grant Likely Cc: Mark Brown Cc: Shawn Guo --- drivers/spi/spi-mxs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c index 282bdd7..6650ded 100644 --- a/drivers/spi/spi-mxs.c +++ b/drivers/spi/spi-mxs.c @@ -445,7 +445,7 @@ static int mxs_spi_transfer_one(struct spi_master *master, * DMA only: 2.164808 seconds, 473.0KB/s * Combined: 1.676276 seconds, 610.9KB/s */ - if (t->len <= 256) { + if (t->len < 32) { writel(BM_SSP_CTRL1_DMA_ENABLE, ssp->base + HW_SSP_CTRL1(ssp) + STMP_OFFSET_REG_CLR); -- 1.7.10.4 ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/