[PATCH i-g-t] tests/perf_pmu: Restore sysfs freq in exit handler

[Vinay Belgaumkar]

Seeing random issues where this test starts with invalid values.
Ensure that we restore the frequencies in case test exits early
due to some system issues.

Link: https://gitlab.freedesktop.org/drm/intel/-/issues/9432
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
---
 tests/intel/perf_pmu.c | 53 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/tests/intel/perf_pmu.c b/tests/intel/perf_pmu.c
index c6e6a8b77..ceacc1d3d 100644
--- a/tests/intel/perf_pmu.c
+++ b/tests/intel/perf_pmu.c
@@ -2454,12 +2454,59 @@ static void pmu_read(int i915)
 		for_each_if((e)->class == I915_ENGINE_CLASS_RENDER) \
 			igt_dynamic_f("%s", e->name)
 
+int fd = -1;
+uint32_t *stash_min, *stash_max, *stash_boost;
+
+static void save_sysfs_freq(int i915)
+{
+	int gt, num_gts, sysfs, tmp;
+
+	num_gts = igt_sysfs_get_num_gt(i915);
+
+	stash_min = (uint32_t *)malloc(sizeof(uint32_t) * num_gts);
+	stash_max = (uint32_t *)malloc(sizeof(uint32_t) * num_gts);
+	stash_boost = (uint32_t *)malloc(sizeof(uint32_t) * num_gts);
+
+	/* Save boost, min and max across GTs */
+	i915_for_each_gt(i915, tmp, gt) {
+		sysfs = igt_sysfs_gt_open(i915, gt);
+		igt_require(sysfs >= 0);
+
+		stash_min[gt] = igt_sysfs_get_u32(sysfs, "rps_min_freq_mhz");
+		stash_max[gt] = igt_sysfs_get_u32(sysfs, "rps_max_freq_mhz");
+		stash_boost[gt] = igt_sysfs_get_u32(sysfs, "rps_boost_freq_mhz");
+		igt_debug("GT: %d, min: %d, max: %d, boost:%d\n",
+			  gt, stash_min[gt], stash_max[gt], stash_boost[gt]);
+
+		close(sysfs);
+	}
+}
+
+static void restore_sysfs_freq(int sig)
+{
+	int sysfs, gt, tmp;
+
+	/* Restore frequencies */
+	i915_for_each_gt(fd, tmp, gt) {
+		sysfs = igt_sysfs_gt_open(fd, gt);
+		igt_require(sysfs >= 0);
+
+		igt_require(__igt_sysfs_set_u32(sysfs, "rps_max_freq_mhz", stash_max[gt]));
+		igt_require(__igt_sysfs_set_u32(sysfs, "rps_min_freq_mhz", stash_min[gt]));
+		igt_require(__igt_sysfs_set_u32(sysfs, "rps_boost_freq_mhz", stash_boost[gt]));
+
+		close(sysfs);
+	}
+	free(stash_min);
+	free(stash_max);
+}
+
 igt_main
 {
 	const struct intel_execution_engine2 *e;
 	unsigned int num_engines = 0;
 	const intel_ctx_t *ctx = NULL;
-	int gt, tmp, fd = -1;
+	int gt, tmp;
 	int num_gt = 0;
 
 	/**
@@ -2482,6 +2529,7 @@ igt_main
 
 		i915_for_each_gt(fd, tmp, gt)
 			num_gt++;
+
 	}
 
 	igt_describe("Verify i915 pmu dir exists and read all events");
@@ -2664,6 +2712,9 @@ igt_main
 	 * Test GPU frequency.
 	 */
 	igt_subtest_with_dynamic("frequency") {
+		save_sysfs_freq(fd);
+		igt_install_exit_handler(restore_sysfs_freq);
+
 		i915_for_each_gt(fd, tmp, gt) {
 			igt_dynamic_f("gt%u", gt)
 				test_frequency(fd, gt);
-- 
2.38.1