From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: [PATCH] i2c: rcar: bail out on zero length transfers Date: Mon, 5 May 2014 18:36:21 +0200 Message-ID: <1399307781-23614-1-git-send-email-wsa@the-dreams.de> Return-path: Sender: linux-sh-owner@vger.kernel.org To: linux-sh@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Wolfram Sang , Magnus Damm , Simon Horman , Laurent Pinchart , linux-i2c@vger.kernel.org, Kuninori Morimoto List-Id: linux-i2c@vger.kernel.org From: Wolfram Sang 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 --- drivers/i2c/busses/i2c-rcar.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index 72a400a73cce..66c952e62f0a 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -552,6 +552,13 @@ 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); @@ -616,7 +623,8 @@ 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 = { -- 1.9.2