[i2c] Two start conditions for PCA9554

Hans J. Koch hjk at linutronix.de
Tue Apr 29 15:11:14 CEST 2008

I have an embedded board with a PCA9554 on it. It's an 8-bit IO expander
similar to the PCF8574 in mainline. One difference is that when reading
from the inputs, you have to do the following:

- start condition
- send slave address, R/W=0
- send command (0x00 = read input register)
- issue another start condition (!)
- send slave address, R/W=1
- read data
- stop condition

Can such a protocol be handled by the i2c subsystem?


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