I have a custom platform with an Arria 10 interfacing to some voltage regulators over SMBUS. Writes to those devices appear to work, but the protocol analyzer I have attached indicates to me that reads are failing because the initial write command also issued a stop bit which causes the transaction to abort. I can read and write all devices on the bus cleanly through the manufacturer's programming dongle and can see that its protocol does not use those stop bits.
I feel that this must be due to something in the bitmasks that I'm using in the linux ioctl configuration or something, but haven't been able to figure it out.
