[PATCH net-next v4 12/14] selftests: dpll: add pin phase adjust test

[Petr Oros <poros@redhat.com>]

Add a test that reads the phase adjustment range and granularity a
pin advertises, picks the largest multiple of the granularity inside
the range, or the smallest one when that is already the current value,
sets it, reads it back and restores the original value. It skips when
the dpll tool lacks the phase-adjust keyword of pin set and when the
range is too narrow to pick a different value. A pin that reports no
phase adjustment or no range is a skip on a device provided by the user
and a failure on the device the script created, whose pins report
both.

The core refuses a value outside the advertised range and one that is
not a multiple of the granularity a driver reports, the current value
included, so a pin that sits at such a value could not be put back. The
test bails out on either before it schedules the restore, which is
deferred right after so that an interrupted run restores the value too.

The granularity is only reported by drivers that have the core enforce
one. Without it the target is computed with a granularity of 1, and a
driver may refuse it for a granularity of its own or for any other
constraint the interface does not advertise. A refused set is therefore
a skip on a device provided by the user, with the reason the tool
reported, and a failure on the device the script created, whose
simulator accepts every value its range and granularity allow. The
test ends there, a value that was not set has nothing to read back.

Reviewed-by: Ivan Vecera <ivecera@redhat.com>
Acked-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Petr Oros <poros@redhat.com>
---
v4:
- bail out when the current value lies outside the advertised range,
  it could not be restored
- tell a failed query from a pin without a phase adjust or a range and
  log a deferred restore that fails

v3:
- follow the move of the selftests to
  tools/testing/selftests/drivers/dpll

v3: https://lore.kernel.org/all/20261109093523.931201-13-poros@redhat.com/
v2: https://lore.kernel.org/all/20261105151852.1844305-13-poros@redhat.com/
v1: https://lore.kernel.org/all/20261103093910.596225-13-poros@redhat.com/
---
 .../selftests/drivers/dpll/dpll_features.sh   | 102 ++++++++++++++++++
 .../selftests/drivers/dpll/dpll_lib.sh        |  15 +++
 2 files changed, 117 insertions(+)

diff --git a/tools/testing/selftests/drivers/dpll/dpll_features.sh b/tools/testing/selftests/drivers/dpll/dpll_features.sh
index ebb52c85262016..7b7e077073db58 100755
--- a/tools/testing/selftests/drivers/dpll/dpll_features.sh
+++ b/tools/testing/selftests/drivers/dpll/dpll_features.sh
@@ -29,6 +29,7 @@ ALL_TESTS="
 	test_pin_state_transitions
 	test_pin_priority_get_set
 	test_pin_frequency_set_get
+	test_pin_phase_adjust_set_get
 "
 
 ##############################################################################
@@ -298,6 +299,107 @@ test_pin_state_transitions()
 	log_test "DPLL pin state transitions"
 }
 
+test_pin_phase_adjust_set_get()
+{
+	local before target after json min max gran reason
+
+	RET=0
+
+	if [ -z "$PIN_TUNE_ID" ]; then
+		dpll_log_test_skip_or_fail "DPLL pin phase-adjust set/get" \
+		    "no spare input pin"
+		return
+	fi
+	if ! dpll_pin_set_supports phase-adjust; then
+		log_test_skip "DPLL pin phase-adjust set/get" \
+		    "dpll tool lacks pin set phase-adjust"
+		return
+	fi
+
+	# A query that failed is not a pin without a phase adjust.
+	if ! before=$(dpll_pin_get_phase_adjust "$PIN_TUNE_ID") ||
+	   ! json=$(dpll_pin_json "$PIN_TUNE_ID"); then
+		check_err 1 "pin $PIN_TUNE_ID query failed"
+		log_test "DPLL pin phase-adjust set/get"
+		return
+	fi
+	if [ -z "$before" ]; then
+		dpll_log_test_skip_or_fail "DPLL pin phase-adjust set/get" \
+		    "phase adjust not reported"
+		return
+	fi
+	if ! [[ "$before" =~ ^-?[0-9]+$ ]]; then
+		check_err 1 "phase adjust '$before' is not a number"
+		log_test "DPLL pin phase-adjust set/get"
+		return
+	fi
+
+	# Pick a target inside the advertised range different from the
+	# current value, a multiple of the granularity, which is taken as 1
+	# when the driver reports none.
+	min=$(jq -r '.["phase-adjust-min"] // empty' <<< "$json")
+	max=$(jq -r '.["phase-adjust-max"] // empty' <<< "$json")
+	gran=$(jq -r '.["phase-adjust-gran"] // empty' <<< "$json")
+	if [ -z "$min" ] || [ -z "$max" ]; then
+		dpll_log_test_skip_or_fail "DPLL pin phase-adjust set/get" \
+		    "no adjust range"
+		return
+	fi
+	# The core refuses a value outside the range or off the
+	# granularity, the current one included. A pin that sits at such a
+	# value could not be put back, so bail out before the restore is
+	# scheduled.
+	if [ "$before" -lt "$min" ] || [ "$before" -gt "$max" ]; then
+		dpll_log_test_skip_or_fail "DPLL pin phase-adjust set/get" \
+		    "current phase adjust outside the adjust range"
+		return
+	fi
+	if [ -n "$gran" ] && [ $((before % gran)) -ne 0 ]; then
+		dpll_log_test_skip_or_fail "DPLL pin phase-adjust set/get" \
+		    "current phase adjust not a granularity multiple"
+		return
+	fi
+	[ -n "$gran" ] || gran=1
+	defer dpll_restore dpll_pin_set_phase_adjust "$PIN_TUNE_ID" "$before"
+
+	# Shell division truncates towards zero, so round the bounds towards
+	# the inside of the range explicitly, which matters for negative ones.
+	target=$((max / gran * gran))
+	[ "$target" -gt "$max" ] && target=$((target - gran))
+	if [ "$target" = "$before" ]; then
+		target=$((min / gran * gran))
+		[ "$target" -lt "$min" ] && target=$((target + gran))
+	fi
+	if [ "$target" = "$before" ] || [ "$target" -gt "$max" ] ||
+	   [ "$target" -lt "$min" ]; then
+		log_test_skip "DPLL pin phase-adjust set/get" "range too narrow"
+		return
+	fi
+
+	# A driver may enforce a granularity it does not report or another
+	# constraint, a skip on a device the user provided, the simulator
+	# accepts every value its range and granularity allow.
+	if ! dpll_pin_set_phase_adjust "$PIN_TUNE_ID" "$target"; then
+		reason=${DPLL_LAST_ERR%%$'\n'*}
+		dpll_log_test_skip_or_fail "DPLL pin phase-adjust set/get" \
+		    "cannot set phase-adjust=$target${reason:+, $reason}"
+		return
+	fi
+	after=$(dpll_pin_get_phase_adjust "$PIN_TUNE_ID")
+	if [ "$after" != "$target" ]; then
+		check_err 1 "phase-adjust expected $target, got '$after'"
+	fi
+
+	dpll_pin_set_phase_adjust "$PIN_TUNE_ID" "$before"
+	check_err $? "cannot restore phase-adjust"
+	after=$(dpll_pin_get_phase_adjust "$PIN_TUNE_ID")
+	if [ "$after" != "$before" ]; then
+		check_err 1 "phase-adjust not restored, got '$after'"
+	fi
+
+	log_test "DPLL pin phase-adjust set/get"
+}
+
 test_pin_frequency_set_get()
 {
 	local before target after reason json
diff --git a/tools/testing/selftests/drivers/dpll/dpll_lib.sh b/tools/testing/selftests/drivers/dpll/dpll_lib.sh
index fa1895ab17f518..6b99dae5a4f379 100644
--- a/tools/testing/selftests/drivers/dpll/dpll_lib.sh
+++ b/tools/testing/selftests/drivers/dpll/dpll_lib.sh
@@ -442,6 +442,11 @@ dpll_pin_get_prio()
 	__dpll_pin_dev_field "$1" "$2" '.prio'
 }
 
+dpll_pin_get_phase_adjust()
+{
+	__dpll_pin_field "$1" '.["phase-adjust"]'
+}
+
 ##############################################################################
 # Pin setters
 #
@@ -496,6 +501,16 @@ dpll_pin_set_frequency()
 			     2>&1 >/dev/null)
 }
 
+# $2: phase adjust in ps
+dpll_pin_set_phase_adjust()
+{
+	local pin_id=$1
+	local phase_adjust=$2
+
+	DPLL_LAST_ERR=$(dpll pin set id "$pin_id" phase-adjust \
+			     "$phase_adjust" 2>&1 >/dev/null)
+}
+
 ##############################################################################
 # dpllsim configfs interface
 #
-- 
2.56.0