[PATCH 3/4] i2c: omap: don't reset controller if Arbitration Lost detected

From: Alexander Kochetkov
Date: Thu Nov 20 2014 - 16:29:50 EST

Arbitration Lost is a expected situation in a multimaster environment.
IP correctly detect it.

The only reason for reseting IP in the AL case is to be sure to
avoid advisory 1.94 (omap3) and errata i595 (omap4):
"I2C: After an Arbitration is Lost the Module Incorrectly Starts
the Next Transfer" with workaround: "The MST and STT bits inside
I2C_CON should be set to 1 at the same moment (avoid setting the
MST bit to 1 while STT = 0)."

The driver never writes MST and STT bits separately and doesn't
create condition for errata. So the reset is not necessary.

Tested on Beagleboard XM C.

Signed-off-by: Alexander Kochetkov <al.kochet@xxxxxxxxx>
drivers/i2c/busses/i2c-omap.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 3ffb9c0..47103e7 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -707,13 +707,17 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
return 0;

/* We have an error */
- if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR |
+ if (dev->cmd_err & (OMAP_I2C_STAT_ROVR |
return -EIO;

+ if (dev->cmd_err & OMAP_I2C_STAT_AL) {
+ return -EIO;
+ }
if (dev->cmd_err & OMAP_I2C_STAT_NACK) {
if (msg->flags & I2C_M_IGNORE_NAK)
return 0;

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