The engine encodes an address-only transaction in command word bit 18,
which is what SMBus Receive Byte and Send Byte need and what was missing
for ee1004 to bind.
The bit is not documented for the PCU function. It was located by
structure rather than by sweeping: SMBCMD on the iMC channel function
(datasheet ref. 614073 section 3.1.8) places PNTR_SEL immediately above
WORD_ACCESS, and word access here is bit 17. Bit 17 had itself been
unknown until it turned out to be word access, and an earlier sweep of
this register covered bits 31:20 only, so 18 was untried rather than
already ruled out.
Validated against the device rather than against the register. An EEPROM
auto-increments its pointer after a read, so priming the pointer and
repeating the read with the bit set has a predicted answer: the next
byte, not the one named. Eight consecutive reads returned SPD bytes 0x01
through 0x08 in order, matching an ordinary dump. Send Byte was confirmed
on the DDR4 page-select addresses, which hold a latch and store no data,
so the page state is itself the readout.
Result: ee1004 binds on all four SPD addresses and decode-dimms decodes
all four modules with both CRCs valid on each. The part number comes off
page 1, so the page select runs end to end. The four module serial
numbers are unchanged from the baseline recorded before this series.
SMBus Quick stays unimplemented. Beyond having no obvious encoding, a
write into the 0x30-0x37 range is how an EE1004 SPD is write-protected,
permanently on many modules, so an adapter on the memory bus should not
advertise a probe that writes. i2cdetect scans in read mode.
Also fix test-smoke.sh resolving the module through modinfo, which
silently tested the installed DKMS build instead of the one just
compiled. It now prefers the local .ko and prints which it loaded.
Smoke suite: 19 passed, 0 failed. checkpatch --strict 0/0/0, in-tree W=1
and Sparse clean.
Simone
c04e0ec5a8