From: Mark Brown <broonie@linaro.org>
Date: Sat, 29 Mar 2014 23:48:07 +0000 (+0000)
Subject: spi: Fix handling of cs_change in core implementation
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=0b73aa63c193006c3d503d4903dd4792a26e1d50;p=deliverable%2Flinux.git

spi: Fix handling of cs_change in core implementation

The core implementation of cs_change didn't follow the documentation
which says that cs_change in the middle of the transfer means to briefly
deassert chip select, instead it followed buggy drivers which change the
polarity of chip select.  Use a delay of 10us between deassert and
reassert simply from pulling numbers out of a hat.

Reported-by: Gerhard Sittig <gsi@denx.de>
Signed-off-by: Mark Brown <broonie@linaro.org>
---

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 23756b0f9036..5d826f047714 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -591,7 +591,6 @@ static int spi_transfer_one_message(struct spi_master *master,
 				    struct spi_message *msg)
 {
 	struct spi_transfer *xfer;
-	bool cur_cs = true;
 	bool keep_cs = false;
 	int ret = 0;
 
@@ -627,8 +626,9 @@ static int spi_transfer_one_message(struct spi_master *master,
 					 &msg->transfers)) {
 				keep_cs = true;
 			} else {
-				cur_cs = !cur_cs;
-				spi_set_cs(msg->spi, cur_cs);
+				spi_set_cs(msg->spi, false);
+				udelay(10);
+				spi_set_cs(msg->spi, true);
 			}
 		}