[PATCH 3/4] mxs/spi: Decrement the DMA/PIO border

Marek Vasut marex at denx.de
Mon Sep 3 22:40:17 EDT 2012

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 <marex at denx.de>
Cc: Chris Ball <cjb at laptop.org>
Cc: Fabio Estevam <fabio.estevam at freescale.com>
Cc: Grant Likely <grant.likely at secretlab.ca>
Cc: Mark Brown <broonie at opensource.wolfsonmicro.com>
Cc: Shawn Guo <shawn.guo at linaro.org>
 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) {
 				ssp->base + HW_SSP_CTRL1(ssp) +

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