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i2c: algo-bit: init the bus to a known state

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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 <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
This commit is contained in:
Wolfram Sang authored and Wolfram Sang committed 2017-12-31 00:16:37 +01:00
1 parent e535376537
commit 3e5f06bed7
1 file changed
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drivers/i2c/algos/i2c-algo-bit.c
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@@ -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;