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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 <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Wolfram Sang 2017-12-04 09:16:18 +01:00 committed by Wolfram Sang
parent e535376537
commit 3e5f06bed7
1 changed files with 5 additions and 0 deletions
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5
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) if (bit_adap->getscl == NULL)
adap->quirks = &i2c_bit_quirk_no_clk_stretch; 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); ret = add_adapter(adap);
if (ret < 0) if (ret < 0)
return ret; return ret;