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TPS65981: Probing for the TPS65981 PD Controller on the I²C bus using SMBus Quick commands

Part Number: TPS65981

I have a TPS65981 EVM connected to the I²C bus of a single-board computer (SBC). The SBC vendor recommends that the board's I²C bus is accessed through the PICMG EAPi, which provides an I²C device probe. However this probe doesn't work with the TPS65981.

Further investigation with a scope showed that the SBC is implementing the device probe using something that looks like SMBus Quick commands, i.e. transmitting the device address and R/W bit, then issuing STOP immediately after the ACK. When the TPS65981's address is probed it appears to get confused and fail to release the pull-down on the bus after ACKing, rendering the bus unusable until the TPS65981 is powered-down.

I have successfully worked around this by creating a custom device probe which attempts to read a single byte from offset zero on all devices. However I'd like to know which SMBus commands the TPS65981 supports. The Tech Reference talks about the "Unique Address Interface Protocol" which uses SMBus block read/write commands, but doesn't explicitly mention that other SMBus commands are't supported.