i2c: rcar: bail out on zero length transfers
authorWolfram Sang <wsa+renesas@sang-engineering.com>
Mon, 5 May 2014 16:36:21 +0000 (18:36 +0200)
committerWolfram Sang <wsa@the-dreams.de>
Wed, 14 May 2014 16:59:57 +0000 (18:59 +0200)
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
drivers/i2c/busses/i2c-rcar.c

index d4fa8eba6e9d2e40e11cb0ccba5ee64606dd8fff..06d47aafbb79c75a18a66e12964544a9a2b3496f 100644 (file)
@@ -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 = {