[IPMBD] ipmbSend handling

[KFTING at nuvoton.com]

Hi:

I check the ipmbd implementation from
https://urldefense.proofpoint.com/v2/url?u=https-3A__gerrit.openbmc-2Dproject.xyz_-23_c_openbmc_ipmbbridge_-2B_11130_&d=DwICAg&c=ue8mO8zgC4VZ4q_aNVKt8G9MC01UFDmisvMR1k-EoDM&r=kGibSCEQz-PilnW-r9KNT7_zWJXJNtnSK5aYZCe7SVs&m=9vYrt5dE5uTcGZ0xJvXwlc2qHu9SzkgJbpR7h9W0jXE&s=xLAMWHrLSU8GJiEb4ObBmfmlBhRwK26Z3t4-piFCe1c&e= and find out that the IPMB request or response messages are passed down to the I2C slave device in the ipmbSend function.

The master device node is /dev/i2c-0 and the slave device node is /sys/bus/i2c/devices/0-1010/slave-mqueue in the ipmbbridge implementation.

The direction is always from the master device to the slave device.

In normal IPMB usage case, an IPMB request is sent to the master device (say /dev/i2c-3) and then the master device sends that IPMB request to the client device attached to the master device's bus.

While an IPMB response returns from the client device, the client device uses an I2C master-write transfer to send the response back to the request originator, which is /dev/i2c-3, according to IPMB spec. So the request originator becomes an I2C slave at this moment.

It seems to me that ipmbSend behavior doesn't get aligned with the description of request/response protocol in IPMB spec.

I might misunderstand the ipmbSend behavior and any comment is welcome.

Thank you.

Regards,
Tyrone


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