[igt-dev] [PATCH i-g-t 15/23] i915/perf: Fix CS timestamp vs OA timstamp mismatch

[Umesh Nerlige Ramappa]

CS timestamp can have an additional configuration that shifts the
timestamp value by a specified number of bits. On DG2, this additional
configuration is ignored by OA, so OA timestamps are missing the shift.

Add newly defined interface to get the exact OA timestamp frequency so
that the deltas can be accurately calculated.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
---
 include/drm-uapi/i915_drm.h |  6 ++++++
 lib/i915/perf.c             |  6 +++++-
 tests/i915/perf.c           | 37 +++++++++++++++++++++++++++++++++++--
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/include/drm-uapi/i915_drm.h b/include/drm-uapi/i915_drm.h
index c7587a0f..11c40811 100644
--- a/include/drm-uapi/i915_drm.h
+++ b/include/drm-uapi/i915_drm.h
@@ -749,6 +749,12 @@ typedef struct drm_i915_irq_wait {
 /* Query if the kernel supports the I915_USERPTR_PROBE flag. */
 #define I915_PARAM_HAS_USERPTR_PROBE 56
 
+/*
+ * Frequency of the timestamps in OA reports. This used to be the same as the CS
+ * timestamp frequency, but differs on some platforms.
+ */
+#define I915_PARAM_OA_TIMESTAMP_FREQUENCY 57
+
 /* Must be kept compact -- no holes and well documented */
 
 typedef struct drm_i915_getparam {
diff --git a/lib/i915/perf.c b/lib/i915/perf.c
index 3f131aaa..2f24cbd8 100644
--- a/lib/i915/perf.c
+++ b/lib/i915/perf.c
@@ -464,7 +464,11 @@ intel_perf_for_fd(int drm_fd)
 	close(sysfs_dir_fd);
 
 	if (getparam(drm_fd, I915_PARAM_CHIPSET_ID, &device_id) ||
-	    getparam(drm_fd, I915_PARAM_REVISION, &device_revision) ||
+	    getparam(drm_fd, I915_PARAM_REVISION, &device_revision))
+		return NULL;
+
+	/* if OA_TIMESTAMP_FREQUENCY is not supported, fall back to CS_TIMESTAMP_FREQUENCY */
+	if (getparam(drm_fd, I915_PARAM_OA_TIMESTAMP_FREQUENCY, &timestamp_frequency) &&
 	    getparam(drm_fd, I915_PARAM_CS_TIMESTAMP_FREQUENCY, &timestamp_frequency))
 		return NULL;
 
diff --git a/tests/i915/perf.c b/tests/i915/perf.c
index 3caf7cac..3eb31f3b 100644
--- a/tests/i915/perf.c
+++ b/tests/i915/perf.c
@@ -453,6 +453,29 @@ gen8_read_report_reason(const uint32_t *report)
 		return "unknown";
 }
 
+static uint32_t
+cs_timestamp_frequency(int fd)
+{
+	struct drm_i915_getparam gp = {};
+	static uint32_t value = 0;
+
+	if (value)
+		return value;
+
+	gp.param = I915_PARAM_CS_TIMESTAMP_FREQUENCY;
+	gp.value = (int *)(&value);
+
+	igt_assert_eq(igt_ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp), 0);
+
+	return value;
+}
+
+static uint64_t
+cs_timebase_scale(uint32_t u32_delta)
+{
+	return ((uint64_t)u32_delta * NSEC_PER_SEC) / cs_timestamp_frequency(drm_fd);
+}
+
 static uint64_t
 timebase_scale(uint32_t u32_delta)
 {
@@ -543,6 +566,15 @@ oa_report_get_ctx_id(uint32_t *report)
 	return report[2];
 }
 
+static int
+oar_unit_default_format(void)
+{
+	if (IS_DG2(devid))
+		return I915_OAR_FORMAT_A32u40_A4u32_B8_C8;
+
+	return test_set->perf_oa_format;
+}
+
 /*
  * Temporary wrapper to distinguish mappings on !llc platforms,
  * where it seems cache over GEM_MMAP_OFFSET is not flushed before execution.
@@ -3959,6 +3991,7 @@ again:
 
 static void gen12_single_ctx_helper(void)
 {
+	uint64_t fmt = oar_unit_default_format();
 	uint64_t properties[] = {
 		/* Have a random value here for the context id, but initialize
 		 * it once you figure out the context ID for the work to be
@@ -3974,7 +4007,7 @@ static void gen12_single_ctx_helper(void)
 		 * values.
 		 */
 		DRM_I915_PERF_PROP_OA_METRICS_SET, test_set->perf_oa_metrics_set,
-		DRM_I915_PERF_PROP_OA_FORMAT, test_set->perf_oa_format,
+		DRM_I915_PERF_PROP_OA_FORMAT, fmt,
 	};
 	struct drm_i915_perf_open_param param = {
 		.flags = I915_PERF_FLAG_FD_CLOEXEC,
@@ -4202,7 +4235,7 @@ static void gen12_single_ctx_helper(void)
 	/* Sanity check that we can pass the delta to timebase_scale */
 	igt_assert(delta_ts64 < UINT32_MAX);
 	delta_oa32_ns = timebase_scale(delta_oa32);
-	delta_ts64_ns = timebase_scale(delta_ts64);
+	delta_ts64_ns = cs_timebase_scale(delta_ts64);
 
 	igt_debug("oa32 delta = %u, = %uns\n",
 			delta_oa32, (unsigned)delta_oa32_ns);
-- 
2.25.1