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Commit af5a60ba authored by Jean Delvare's avatar Jean Delvare Committed by Jean Delvare
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i2c-algo-bit: Complain about masters which can't read SCL 



The I2C specification explicitly describes both SDA and SCL as
bidirectional lines. An I2C master with a read-only SCL is thus not
compliant. If a slow slave stretches the clock, errors will happen,
so the bus can't be considered as reliable.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent f451171c

drivers/i2c/algos/i2c-algo-bit.c

+12 −2
Original line number Diff line number Diff line
@@ -604,9 +604,10 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, 
			     int (*add_adapter)(struct i2c_adapter *))

{

	struct i2c_algo_bit_data *bit_adap = adap->algo_data;

	int ret;



	if (bit_test) {

		int ret = test_bus(bit_adap, adap->name);

		ret = test_bus(bit_adap, adap->name);

		if (ret < 0)

			return -ENODEV;

	}
@@ -615,7 +616,16 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, 
	adap->algo = &i2c_bit_algo;

	adap->retries = 3;



	return add_adapter(adap);

	ret = add_adapter(adap);

	if (ret < 0)

		return ret;



	/* Complain if SCL can't be read */

	if (bit_adap->getscl == NULL) {

		dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");

		dev_warn(&adap->dev, "Bus may be unreliable\n");

	}

	return 0;

}



int i2c_bit_add_bus(struct i2c_adapter *adap)