Simone
c04e0ec5a8
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.
201 lines
6.2 KiB
Bash
Executable File
201 lines
6.2 KiB
Bash
Executable File
#!/usr/bin/env bash
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#
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# WRITES TO THE BUS. Tests whether the pointer-select bit found by
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# tools/probe-pntr-sel.sh also produces an SMBus Send Byte, the write half of
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# I2C_FUNC_SMBUS_BYTE, which ee1004 needs to select a DDR4 SPD page.
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#
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# The target is the page-select address 0x36 or 0x37, never an EEPROM. Those
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# addresses hold a single latch and store no data: the only effect a write can
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# have there is to select page 0 or page 1. Nothing is written to 0x50-0x57.
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#
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# The test verifies itself. A DDR4 SPD is 512 bytes reached through a 256-byte
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# window, so which page is latched is visible in the data: on page 0 byte 0x00
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# is 0x23 (the JEDEC "512 byte SPD" code), on page 1 the same offset shows
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# byte 0x100 instead, which is not 0x23. Issue the Send Byte, read byte 0x00
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# back, and the page state is the answer.
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#
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# --restore is the safe first run. It targets a channel already latched on page
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# 1 and selects page 0, so a working Send Byte repairs that channel and a
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# broken one leaves it exactly as it was found. There is no outcome worse than
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# the starting state.
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#
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# --flip runs the full round trip on a channel already on page 0: select page 1,
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# confirm the data moved, select page 0 again, confirm it came back. Use it only
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# after --restore has shown the encoding works.
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#
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set -euo pipefail
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# shellcheck source=tools/common.sh
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source "$(dirname "$(readlink -f "$0")")/common.sh"
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COMMAND_TOGGLE=$((1 << 29))
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GO_BIT=$((1 << 19))
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PNTR_SEL_BIT=$((1 << 18))
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TSOD_ACTIVE_BIT=$((1 << 20))
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WRITE_OPERATION=$((1 << 15))
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STAT_BUSY=1
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STAT_ERROR=2
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SPD_ADDR=0x50
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PAGE0_ADDR=0x36
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PAGE1_ADDR=0x37
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SPD_PAGE0_BYTE0=0x23
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CHANNEL=0
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MODE=restore
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CONFIRMED=false
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while (($#)); do
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case $1 in
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--i-understand) CONFIRMED=true; shift ;;
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--channel) CHANNEL=$2; shift 2 ;;
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--restore) MODE=restore; shift ;;
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--flip) MODE=flip; shift ;;
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-h|--help)
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sed -n '3,24p' "$0"
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echo "usage: $0 --i-understand --channel 0|1 [--restore|--flip]"
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exit 0
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;;
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*) die "unknown argument: $1" ;;
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esac
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done
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$CONFIRMED || {
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echo "This writes to the SPD page-select address. Re-run with --i-understand." >&2
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exit 2
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}
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require_root
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require_cmd lspci setpci awk
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case $CHANNEL in
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0) REG_DATA=$REG_CH0_DATA; REG_STAT=$REG_CH0_STAT; REG_CTRL=$REG_CH0_CTRL ;;
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1) REG_DATA=$REG_CH1_DATA; REG_STAT=$REG_CH1_STAT; REG_CTRL=$REG_CH1_CTRL ;;
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*) die "channel must be 0 or 1" ;;
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esac
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driver_is_loaded && die "unload i2c-imc-skylake first"
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BDF=$(find_pcu)
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original_data=$(read_reg "$BDF" "$REG_DATA")
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original_ctrl=$(read_reg "$BDF" "$REG_CTRL")
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status0=$(read_reg "$BDF" "$REG_STAT")
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((original_data & GO_BIT)) && die "GO already set, refusing"
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((original_data & TSOD_ACTIVE_BIT)) && die "TSOD_ACTIVE set, refusing"
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((status0 & STAT_BUSY)) && die "engine BUSY, refusing"
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restore()
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{
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setpci -s "$BDF" "$REG_DATA.L=$(printf '%08x' "$((original_data & ~GO_BIT))")" || true
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setpci -s "$BDF" "$REG_CTRL.L=$(printf '%08x' "$original_ctrl")" || true
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}
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trap restore EXIT
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# wait_idle -> echoes the final status
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wait_idle()
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{
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local i data
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for ((i = 0; i < 60; i++)); do
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data=$(read_reg "$BDF" "$REG_DATA")
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((data & GO_BIT)) || break
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sleep 0.005
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done
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read_reg "$BDF" "$REG_STAT"
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}
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# spd_byte0 -> echoes the byte at SPD offset 0x00 as 0x%02x
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spd_byte0()
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{
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local ctrl
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setpci -s "$BDF" \
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"$REG_DATA.L=$(printf '%08x' "$((COMMAND_TOGGLE | GO_BIT | (SPD_ADDR << 8)))")"
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wait_idle >/dev/null
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ctrl=$(read_reg "$BDF" "$REG_CTRL")
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printf '0x%02x\n' "$((ctrl & 0xff))"
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}
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# send_byte <addr> -> echoes the status; returns 1 if the device NACKed
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send_byte()
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{
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local addr=$1 command status
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command=$((COMMAND_TOGGLE | GO_BIT | PNTR_SEL_BIT | WRITE_OPERATION | (addr << 8)))
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# Data byte in the same place a BYTE_DATA write puts it. The page-select
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# devices ignore it; it is set to zero so nothing meaningful is sent.
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setpci -s "$BDF" "$REG_CTRL.L=00000000"
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printf ' Send Byte to %s: command 0x%08x\n' "$addr" "$command"
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setpci -s "$BDF" "$REG_DATA.L=$(printf '%08x' "$command")"
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status=$(wait_idle)
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printf ' status 0x%s\n' "${status#0x}"
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# A NACK here is expected and harmless: some modules latch the page but
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# do not acknowledge, which is why ee1004 rechecks instead of giving up.
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! ((status & STAT_ERROR))
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}
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echo "device $BDF channel $CHANNEL, mode $MODE"
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echo "DATA before: $original_data CTRL before: $original_ctrl STATUS: $status0"
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echo
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before=$(spd_byte0)
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printf 'SPD 0x50 byte 0x00 before: %s\n' "$before"
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case $MODE in
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restore)
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if [[ "$before" == "$SPD_PAGE0_BYTE0" ]]; then
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die "channel $CHANNEL is already on page 0, nothing to restore (use --flip)"
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fi
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echo "channel is not on page 0. Selecting page 0."
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send_byte "$PAGE0_ADDR" || echo " (device did not ack; checking anyway)"
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after=$(spd_byte0)
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printf 'SPD 0x50 byte 0x00 after: %s\n\n' "$after"
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if [[ "$after" == "$SPD_PAGE0_BYTE0" ]]; then
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cat <<-EOF
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=== SEND BYTE WORKS ===
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The page-select address accepted an address-only write: byte 0x00 went
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from $before to $after, the JEDEC page-0 value. Bit 18 encodes SMBus
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Send Byte as well as Receive Byte, so I2C_FUNC_SMBUS_BYTE can be
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implemented honestly and ee1004 can bind.
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Channel $CHANNEL is also back on page 0, which is where it should have
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been.
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EOF
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else
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cat <<-EOF
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=== NO PAGE CHANGE ===
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Byte 0x00 is still $after. Either the write did not reach the bus in
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Send Byte form, or this channel is not on page 1 for the reason
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assumed. The channel is exactly as it was found; nothing was made
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worse. Do not implement Send Byte on this encoding.
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EOF
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fi
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;;
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flip)
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[[ "$before" == "$SPD_PAGE0_BYTE0" ]] ||
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die "channel $CHANNEL is not on page 0 to begin with (byte 0x00 = $before)"
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echo "selecting page 1"
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send_byte "$PAGE1_ADDR" || echo " (no ack; checking anyway)"
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flipped=$(spd_byte0)
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printf 'byte 0x00 on page 1: %s\n\n' "$flipped"
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echo "selecting page 0 again"
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send_byte "$PAGE0_ADDR" || echo " (no ack; checking anyway)"
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back=$(spd_byte0)
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printf 'byte 0x00 restored: %s\n\n' "$back"
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echo "=== result ==="
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if [[ "$flipped" != "$before" && "$back" == "$before" ]]; then
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echo "Round trip clean: the page moved and came back. Send Byte confirmed."
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elif [[ "$back" != "$before" ]]; then
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echo "WARNING: the channel did not return to page 0 (byte 0x00 = $back)."
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echo "Re-run with --restore to put it back."
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else
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echo "The page never moved. Send Byte is not encoded this way."
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fi
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;;
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esac
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