From 3e5f06bed72fe72166a6778f630241a893f67799 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Mon, 4 Dec 2017 09:16:18 +0100 Subject: i2c: algo-bit: init the bus to a known state Ensure the bus is free when we register the adapter. Before the SCL/SDA wires were in an unknown state. It used to work because sending a byte has a retry mechanism which was triggered if the bus was initially in a non-free state. But the graceful way to do it is to initialize correctly. Signed-off-by: Wolfram Sang Signed-off-by: Wolfram Sang --- drivers/i2c/algos/i2c-algo-bit.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index 1147bddb8b2c..3df0efd69ae3 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -649,6 +649,11 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, if (bit_adap->getscl == NULL) adap->quirks = &i2c_bit_quirk_no_clk_stretch; + /* Bring bus to a known state. Looks like STOP if bus is not free yet */ + setscl(bit_adap, 1); + udelay(bit_adap->udelay); + setsda(bit_adap, 1); + ret = add_adapter(adap); if (ret < 0) return ret; -- cgit v1.2.3