[igt-dev] [PATCH i-g-t] tests/perf_pmu: Compare against requested freq in frequency subtest

[Ashutosh Dixit]

With SLPC, even when we set the same min and max freq's, the requested and
actual freq's can differ from the min/max freq set. For example "efficient
freq" (when in effect) can override set min/max freq. In general FW is the
final arbiter in determining freq and can override set values.

Therefore in igt at perf_pmu@frequency subtest, compare the requested freq
reported by PMU not against the set freq's but against the requested freq
reported in sysfs. Also add a delay after setting freq's to account for
messaging delays in setting freq's in GuC.

v2: Introduce a 100 ms delay after setting freq
v3: Update commit message, code identical to v2

Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/6806
Cc: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
---
 tests/i915/perf_pmu.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/tests/i915/perf_pmu.c b/tests/i915/perf_pmu.c
index f363db2ba13..02f6ae989b1 100644
--- a/tests/i915/perf_pmu.c
+++ b/tests/i915/perf_pmu.c
@@ -1543,10 +1543,13 @@ test_interrupts_sync(int gem_fd)
 	igt_assert_lte(target, busy);
 }
 
+/* Wait for GuC SLPC freq changes to take effect */
+#define wait_freq_set()		usleep(100000)
+
 static void
 test_frequency(int gem_fd)
 {
-	uint32_t min_freq, max_freq, boost_freq;
+	uint32_t min_freq, max_freq, boost_freq, min_req, max_req;
 	uint64_t val[2], start[2], slept;
 	double min[2], max[2];
 	igt_spin_t *spin;
@@ -1572,10 +1575,11 @@ test_frequency(int gem_fd)
 	 * Set GPU to min frequency and read PMU counters.
 	 */
 	igt_require(igt_sysfs_set_u32(sysfs, "gt_min_freq_mhz", min_freq));
-	igt_require(igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz") == min_freq);
 	igt_require(igt_sysfs_set_u32(sysfs, "gt_max_freq_mhz", min_freq));
-	igt_require(igt_sysfs_get_u32(sysfs, "gt_max_freq_mhz") == min_freq);
 	igt_require(igt_sysfs_set_u32(sysfs, "gt_boost_freq_mhz", min_freq));
+	wait_freq_set();
+	igt_require(igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz") == min_freq);
+	igt_require(igt_sysfs_get_u32(sysfs, "gt_max_freq_mhz") == min_freq);
 	igt_require(igt_sysfs_get_u32(sysfs, "gt_boost_freq_mhz") == min_freq);
 
 	gem_quiescent_gpu(gem_fd); /* Idle to be sure the change takes effect */
@@ -1587,6 +1591,7 @@ test_frequency(int gem_fd)
 
 	min[0] = 1e9*(val[0] - start[0]) / slept;
 	min[1] = 1e9*(val[1] - start[1]) / slept;
+	min_req = igt_sysfs_get_u32(sysfs, "gt_cur_freq_mhz");
 
 	igt_spin_free(gem_fd, spin);
 	gem_quiescent_gpu(gem_fd); /* Don't leak busy bo into the next phase */
@@ -1597,11 +1602,11 @@ test_frequency(int gem_fd)
 	 * Set GPU to max frequency and read PMU counters.
 	 */
 	igt_require(igt_sysfs_set_u32(sysfs, "gt_max_freq_mhz", max_freq));
-	igt_require(igt_sysfs_get_u32(sysfs, "gt_max_freq_mhz") == max_freq);
 	igt_require(igt_sysfs_set_u32(sysfs, "gt_boost_freq_mhz", boost_freq));
-	igt_require(igt_sysfs_get_u32(sysfs, "gt_boost_freq_mhz") == boost_freq);
-
 	igt_require(igt_sysfs_set_u32(sysfs, "gt_min_freq_mhz", max_freq));
+	wait_freq_set();
+	igt_require(igt_sysfs_get_u32(sysfs, "gt_max_freq_mhz") == max_freq);
+	igt_require(igt_sysfs_get_u32(sysfs, "gt_boost_freq_mhz") == boost_freq);
 	igt_require(igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz") == max_freq);
 
 	gem_quiescent_gpu(gem_fd);
@@ -1613,6 +1618,7 @@ test_frequency(int gem_fd)
 
 	max[0] = 1e9*(val[0] - start[0]) / slept;
 	max[1] = 1e9*(val[1] - start[1]) / slept;
+	max_req = igt_sysfs_get_u32(sysfs, "gt_cur_freq_mhz");
 
 	igt_spin_free(gem_fd, spin);
 	gem_quiescent_gpu(gem_fd);
@@ -1621,6 +1627,7 @@ test_frequency(int gem_fd)
 	 * Restore min/max.
 	 */
 	igt_sysfs_set_u32(sysfs, "gt_min_freq_mhz", min_freq);
+	wait_freq_set();
 	if (igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz") != min_freq)
 		igt_warn("Unable to restore min frequency to saved value [%u MHz], now %u MHz\n",
 			 min_freq, igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz"));
@@ -1633,12 +1640,12 @@ test_frequency(int gem_fd)
 	igt_info("Max frequency: requested %.1f, actual %.1f\n",
 		 max[0], max[1]);
 
-	assert_within_epsilon(min[0], min_freq, tolerance);
+	assert_within_epsilon(min[0], min_req, tolerance);
 	/*
 	 * On thermally throttled devices we cannot be sure maximum frequency
 	 * can be reached so use larger tolerance downards.
 	 */
-	__assert_within_epsilon(max[0], max_freq, tolerance, 0.15f);
+	__assert_within_epsilon(max[0], max_req, tolerance, 0.15f);
 }
 
 static void
-- 
2.38.1