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
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index d4fa8eb..06d47aa 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -561,6 +561,12 @@
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 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 = {