From d7653964c590ba846aa11a8f6edf409773cbc492 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Mon, 5 May 2014 18:36:21 +0200 Subject: [PATCH] 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 Signed-off-by: Wolfram Sang Cc: stable@kernel.org --- drivers/i2c/busses/i2c-rcar.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index d4fa8eba6e9d..06d47aafbb79 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -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 = { -- 2.20.1