Current implementation of the pmbus core driver treats the read request
for page 255 as invalid request and sets the invalid command bit (bit 7)
in the STATUS_CML register. As per the PMBus specification it is a valid
request.
Refer to the PMBus specification, revision 1.3.1, section 11.10 PAGE,
on the page 58:
"Setting the PAGE to FFh means that all subsequent comands are to be
applied to all outputs.
Some commands, such as READ_TEMPERATURE, may use a common sensor but
be available on all pages of a device. Such implementations are the
decision of each device manufacturer or are specified in a PMBus
Application Profile. Consult the manufacturer's documents or the
Application Profile Specification as needed."
For e.g.,
The VOUT_MODE is a valid command for page 255 for maxim 31785 device.
refer to Table 1. PMBus Command Codes on page 14 in the datasheet.
https://datasheets.maximintegrated.com/en/ds/MAX31785.pdf
Fixes: 38870253f1d1 ("hw/i2c: pmbus: fix error returns and guard against out of range accesses")
Signed-off-by: Maheswara Kurapati <quic_mkurapat@quicinc.com>
Signed-off-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Reviewed-by: Titus Rwantare <titusr@google.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220627154703.148943-4-quic_jaehyoo@quicinc.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
dd0b3271e5