Simone
5988db06ad
The CI shellcheck step would have failed on three unused variables. Two were leftovers in probe-cf8-transaction.sh from before the status decoding was simplified; the third was a loop counter in probe-imc-documented.sh that nothing reads. While there: probe-cf8-transaction.sh still described itself in terms of "patch 1/2 of the series", which no longer exists precisely because of what this script measured. Reworded to say what it establishes and why it is kept.
153 lines
4.7 KiB
Bash
Executable File
153 lines
4.7 KiB
Bash
Executable File
#!/usr/bin/env bash
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#
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# WRITES TO HARDWARE. Answers the question that decided this driver's config
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# access method: does a command written through CF8/CFC actually start an SMBus
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# transaction, or only land in the register?
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#
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# It does start one. That result retired an earlier plan to reach the registers
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# through ECAM with a PCI-core change; the driver uses the ordinary config
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# accessors instead. Kept so anyone can reproduce it on their own board.
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#
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# tools/probe-cf8-write.sh already showed that the register itself is writable
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# through CF8/CFC. This issues a full command with the GO bit set and watches
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# whether the engine acts on it.
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#
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# The target defaults to a read of address 0x77, which is not populated, so the
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# only thing that can happen on the bus is an address NACK - the same operation
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# test-smoke.sh already performs through the driver. The original DATA value is
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# restored with GO masked on every exit path.
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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=$((1 << 19))
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TSOD_ACTIVE_BIT=$((1 << 20))
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STAT_BUSY=1
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STAT_ERROR=2
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ADDR=0x77
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REG=0x00
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CHANNEL=0
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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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--addr) ADDR=$2; shift 2 ;;
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--reg) REG=$2; shift 2 ;;
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--channel) CHANNEL=$2; shift 2 ;;
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-h|--help)
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sed -n '3,15p' "$0"
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echo "usage: $0 --i-understand [--addr 0xNN] [--reg 0xNN] [--channel 0|1]"
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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 issues an SMBus read transaction from userspace. 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=$(read_reg "$BDF" "$REG_DATA")
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status0=$(read_reg "$BDF" "$REG_STAT")
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ctrl0=$(read_reg "$BDF" "$REG_CTRL")
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echo "device: $BDF, channel $CHANNEL"
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echo "target: read address $ADDR register $REG"
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echo "DATA before: $original"
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echo "STATUS before: $status0"
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echo "CTRL before: $ctrl0"
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echo
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((original & GO_BIT)) && die "GO already set, refusing"
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((original & TSOD_ACTIVE_BIT)) && die "TSOD_ACTIVE set, refusing"
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((status0 & STAT_BUSY)) && die "engine BUSY, refusing"
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restore()
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{
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setpci -s "$BDF" "$REG_DATA.L=$(printf '%08x' "$((original & ~GO_BIT))")" || true
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echo
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echo "DATA restored to $(read_reg "$BDF" "$REG_DATA")"
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}
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trap restore EXIT
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issue()
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{
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local command=$1 label=$2
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local i data status ctrl go_seen=no changed=no
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printf '=== %s: writing 0x%08x ===\n' "$label" "$command"
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setpci -s "$BDF" "$REG_DATA.L=$(printf '%08x' "$command")"
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for i in $(seq 1 40); do
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data=$(read_reg "$BDF" "$REG_DATA")
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status=$(read_reg "$BDF" "$REG_STAT")
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((data & GO_BIT)) && go_seen=yes
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[[ "$status" != "$status0" ]] && changed=yes
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if ((i <= 3)) || [[ "$changed" == yes ]]; then
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printf ' poll %-2d DATA=%s STATUS=%s\n' "$i" "$data" "$status"
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fi
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((data & GO_BIT)) || break
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sleep 0.005
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done
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data=$(read_reg "$BDF" "$REG_DATA")
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status=$(read_reg "$BDF" "$REG_STAT")
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ctrl=$(read_reg "$BDF" "$REG_CTRL")
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echo " final DATA=$data STATUS=$status CTRL=$ctrl"
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echo " GO observed set: $go_seen"
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echo " STATUS changed: $changed (baseline $status0)"
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if ((status & STAT_ERROR)); then
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echo " -> ERROR/NACK bit set: the engine ran the transaction and the"
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echo " device did not answer, which is the expected result here."
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fi
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echo
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}
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# 1: exactly what the driver writes - toggle bit forced to 1.
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issue $((COMMAND_TOGGLE | GO_BIT | (ADDR << 8) | REG)) "same toggle as the driver"
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# 2: the toggle bit inverted relative to what is in the register now, in case
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# the engine latches a command on a change of that bit rather than on GO.
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issue $(( ((original ^ COMMAND_TOGGLE) & COMMAND_TOGGLE) | GO_BIT | (ADDR << 8) | REG )) \
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"toggle bit inverted"
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echo "=== verdict ==="
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final_status=$(read_reg "$BDF" "$REG_STAT")
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if [[ "$final_status" != "$status0" ]]; then
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cat <<-EOF
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CF8/CFC STARTED A TRANSACTION.
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STATUS moved from $status0 to $final_status without any ECAM access.
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No ECAM access is needed: the driver can use pci_read_config_dword()
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and pci_write_config_dword() like any other driver. This is the
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result the current driver is built on.
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EOF
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else
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cat <<-EOF
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NO TRANSACTION.
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The register accepted the write (probe-cf8-write.sh proved that) but the
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engine did not act on it: STATUS never moved from $status0. On this board
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the failure would not be a filtered write but a command the engine
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ignores when it arrives this way, and the driver's assumption that the
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ordinary config accessors are enough would not hold here.
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EOF
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fi
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