commit 0f1411bc8dade4472ca802f46f75714e67301bb0
author Fabio Estevam <fabio.estevam@freescale.com> Tue Apr 09 13:06:25 2013 +0000
committer Stefano Babic <sbabic@denx.de> Sat Apr 13 17:46:42 2013 +0200
tree 38bb65f86352d2da7a20452e92076908b96f9faf
parent 66300ac25b70018c81c931c981317f6ba390182d

spi: mxc_spi: Set master mode for all channels

The glitch in the SPI clock line, which commit 3cea335c34 (spi: mxc_spi: Fix spi
clock glitch durant reset) solved, is back now and itwas re-introduced by
commit d36b39bf0d (spi: mxc_spi: Fix ECSPI reset handling).

Actually the glitch is happening due to always toggling between slave mode
and master mode by configuring the CHANNEL_MODE bits in this reset function.

Since the spi driver only supports master mode, set the mode for all channels
always to master mode in order to have a stable, "glitch-free" SPI clock line.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

drivers/spi/mxc_spi.c

diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c
index 4c19e0b..20419e6 100644
--- a/drivers/spi/mxc_spi.c
+++ b/drivers/spi/mxc_spi.c
@@ -137,11 +137,15 @@
 		return -1;
 	}
 
-	/* Reset spi */
-	reg_write(&regs->ctrl, 0);
-	reg_write(&regs->ctrl, MXC_CSPICTRL_EN);
-
-	reg_ctrl = reg_read(&regs->ctrl);
+	/*
+	 * Reset SPI and set all CSs to master mode, if toggling
+	 * between slave and master mode we might see a glitch
+	 * on the clock line
+	 */
+	reg_ctrl = MXC_CSPICTRL_MODE_MASK;
+	reg_write(&regs->ctrl, reg_ctrl);
+	reg_ctrl |=  MXC_CSPICTRL_EN;
+	reg_write(&regs->ctrl, reg_ctrl);
 
 	/*
 	 * The following computation is taken directly from Freescale's code.
@@ -174,9 +178,6 @@
 	reg_ctrl = (reg_ctrl & ~MXC_CSPICTRL_POSTDIV(0x0F)) |
 		MXC_CSPICTRL_POSTDIV(post_div);
 
-	/* always set to master mode */
-	reg_ctrl |= 1 << (cs + 4);
-
 	/* We need to disable SPI before changing registers */
 	reg_ctrl &= ~MXC_CSPICTRL_EN;