[PATCH i-g-t] tests/xe_gt_freq: Avoid RPe usage in subtests

[Vinay Belgaumkar <vinay.belgaumkar@intel.com>]

We are seeing several instances where the RPe, which can be altered by
pcode dynamically, is causing subtests to fail randomly. Instead of relying
on it, we can use a mid frequency value for these subtests and avoid these
failures.

Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2262
Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2256

Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
---
 tests/intel/xe_gt_freq.c | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/tests/intel/xe_gt_freq.c b/tests/intel/xe_gt_freq.c
index 93ebb5ed0..442f5658f 100644
--- a/tests/intel/xe_gt_freq.c
+++ b/tests/intel/xe_gt_freq.c
@@ -26,6 +26,9 @@
 #include <sys/time.h>
 
 #define MAX_N_EXEC_QUEUES 16
+#define GT_FREQUENCY_MULTIPLIER	50
+#define GT_FREQUENCY_SCALER	3
+#define FREQ_UNIT_MHZ (GT_FREQUENCY_MULTIPLIER / GT_FREQUENCY_SCALER)
 
 /*
  * Too many intermediate components and steps before freq is adjusted
@@ -70,6 +73,16 @@ static uint32_t get_freq(int fd, int gt_id, const char *freq_name)
 	return freq;
 }
 
+static bool within_expected_range(uint32_t freq, uint32_t val)
+{
+	/*
+	 * GT Frequencies are requested at units of 16.66 Mhz, so allow
+	 * that tolerance.
+	 */
+	return (freq <= val + FREQ_UNIT_MHZ) ||
+		(freq >= val - FREQ_UNIT_MHZ);
+}
+
 static uint32_t rpe(int fd, int gt_id)
 {
 	return get_freq(fd, gt_id, "rpe");
@@ -128,6 +141,8 @@ static void test_freq_basic_api(int fd, int gt_id)
 {
 	uint32_t rpn = get_freq(fd, gt_id, "rpn");
 	uint32_t rp0 = get_freq(fd, gt_id, "rp0");
+	uint32_t rpmid = (rp0 + rpn) / 2;
+	uint32_t min_freq, max_freq;
 
 	/*
 	 * Negative bound tests
@@ -142,16 +157,18 @@ static void test_freq_basic_api(int fd, int gt_id)
 	/* Assert min requests are respected from rp0 to rpn */
 	igt_assert(set_freq(fd, gt_id, "min", rp0) > 0);
 	igt_assert(get_freq(fd, gt_id, "min") == rp0);
-	igt_assert(set_freq(fd, gt_id, "min", rpe(fd, gt_id)) > 0);
-	igt_assert(get_freq(fd, gt_id, "min") == rpe(fd, gt_id));
+	igt_assert(set_freq(fd, gt_id, "min", rpmid) > 0);
+	min_freq = get_freq(fd, gt_id, "min");
+	igt_assert(within_expected_range(min_freq, rpmid));
 	igt_assert(set_freq(fd, gt_id, "min", rpn) > 0);
 	igt_assert(get_freq(fd, gt_id, "min") == rpn);
 
 	/* Assert max requests are respected from rpn to rp0 */
 	igt_assert(set_freq(fd, gt_id, "max", rpn) > 0);
 	igt_assert(get_freq(fd, gt_id, "max") == rpn);
-	igt_assert(set_freq(fd, gt_id, "max", rpe(fd, gt_id)) > 0);
-	igt_assert(get_freq(fd, gt_id, "max") == rpe(fd, gt_id));
+	igt_assert(set_freq(fd, gt_id, "max", rpmid) > 0);
+	max_freq = get_freq(fd, gt_id, "min");
+	igt_assert(within_expected_range(max_freq, rpmid));
 	igt_assert(set_freq(fd, gt_id, "max", rp0) > 0);
 	igt_assert(get_freq(fd, gt_id, "max") == rp0);
 }
@@ -168,6 +185,8 @@ static void test_freq_fixed(int fd, int gt_id, bool gt_idle)
 {
 	uint32_t rpn = get_freq(fd, gt_id, "rpn");
 	uint32_t rp0 = get_freq(fd, gt_id, "rp0");
+	uint32_t rpmid = (rp0 + rpn) / 2;
+	uint32_t cur_freq, act_freq;
 
 	igt_debug("Starting testing fixed request\n");
 
@@ -190,17 +209,19 @@ static void test_freq_fixed(int fd, int gt_id, bool gt_idle)
 		igt_assert(get_freq(fd, gt_id, "act") == rpn);
 	}
 
-	igt_assert(set_freq(fd, gt_id, "min", rpe(fd, gt_id)) > 0);
-	igt_assert(set_freq(fd, gt_id, "max", rpe(fd, gt_id)) > 0);
+	igt_assert(set_freq(fd, gt_id, "min", rpmid) > 0);
+	igt_assert(set_freq(fd, gt_id, "max", rpmid) > 0);
 	usleep(ACT_FREQ_LATENCY_US);
-	igt_assert(get_freq(fd, gt_id, "cur") == rpe(fd, gt_id));
+	cur_freq = get_freq(fd, gt_id, "cur");
+	igt_assert(within_expected_range(cur_freq, rpmid));
 
 	if (gt_idle) {
 		igt_assert_f(igt_wait(xe_is_gt_in_c6(fd, gt_id), 1000, 10),
 			     "GT %d should be in C6\n", gt_id);
 		igt_assert(get_freq(fd, gt_id, "act") == 0);
 	} else {
-		igt_assert(get_freq(fd, gt_id, "act") == rpe(fd, gt_id));
+		act_freq = get_freq(fd, gt_id, "act");
+		igt_assert(within_expected_range(act_freq, rpmid));
 	}
 
 	igt_assert(set_freq(fd, gt_id, "min", rp0) > 0);
-- 
2.38.1