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i2c: rcar: bail out on zero length transfers 

This hardware does not support zero length transfers. Instead, the
driver does one (random) byte transfers currently with undefined results
for the slaves. We now bail out.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
This commit is contained in:
Wolfram Sang 2014-05-05 18:36:21 +02:00 committed by Wolfram Sang
parent fa01d096bf
commit d7653964c5
1 changed files with 8 additions and 1 deletions
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9
drivers/i2c/busses/i2c-rcar.c
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@ -561,6 +561,12 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
ret = -EINVAL;
for (i = 0; i < num; i++) {
/* This HW can't send STOP after address phase */
if (msgs[i].len == 0) {
ret = -EOPNOTSUPP;
break;
}
/*-------------- spin lock -----------------*/
spin_lock_irqsave(&priv->lock, flags);
@ -625,7 +631,8 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
static u32 rcar_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
/* This HW can't do SMBUS_QUICK and NOSTART */
return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
}
static const struct i2c_algorithm rcar_i2c_algo = {