[PATCH i-g-t 2/3] tests/intel/xe_pmu: Add check for the other drm clients using the device

[Soham Purkait <soham.purkait@intel.com>]

If other processes are using the DRM device while idle residency test
is running, GPU engines may be in use, and idle residency might be lower
than expected leading to false positives.
To help identify this issue, a check for the DRM clients, except the very
test, is used and a warning message is printed if any such processes
are found and the test is skipped.

Signed-off-by: Soham Purkait <soham.purkait@intel.com>
---
 tests/intel/xe_pmu.c | 27 +++++++++++++++++++++++++--
 tests/meson.build    |  1 +
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/tests/intel/xe_pmu.c b/tests/intel/xe_pmu.c
index fb4b871e7..c907b6207 100644
--- a/tests/intel/xe_pmu.c
+++ b/tests/intel/xe_pmu.c
@@ -100,6 +100,7 @@
 #include "igt_sysfs.h"
 
 #include "xe/xe_gt.h"
+#include "igt_drm_clients.h"
 #include "xe/xe_ioctl.h"
 #include "xe/xe_spin.h"
 #include "xe/xe_sriov_admin.h"
@@ -865,17 +866,39 @@ static void engine_activity_multi_client(int fd, struct drm_xe_engine_class_inst
 
 static void test_gt_c6_idle(int xe, unsigned int gt)
 {
-	int pmu_fd;
+	int pmu_fd, num_clients = 0;
 	uint64_t pmu_config;
 	uint64_t ts[2];
-	unsigned long slept, start, end;
+	unsigned long slept, start, end, wait = 100000;
 	uint64_t val;
+	struct igt_drm_client_proc *procs = NULL;
 
 	/* Get the PMU config for the gt-c6 event */
 	pmu_config = get_event_config(gt, NULL, "gt-c6-residency");
 
 	pmu_fd = open_pmu(xe, pmu_config);
 
+	/* Wait for other processes using the DRM device ends */
+	for (int pass = 0; pass < 50; pass++) {
+		if (!igt_drm_get_client_procs(xe, getpid(), NULL))
+			break;
+		usleep(wait);
+	}
+
+	num_clients = igt_drm_get_client_procs(xe, getpid(), &procs);
+
+	/* Check if any process is still using the DRM device */
+	if (num_clients) {
+		for (unsigned int i = 0; i < num_clients; i++) {
+			igt_warn("%s (pid=%u client=%lu) is using DRM device.\n",
+				 procs[i].print_name, procs[i].pid, procs[i].id);
+		}
+		free(procs);
+		procs = NULL;
+		igt_skip("As other processes are using the DRM device, "
+			 "measured idle_residency may be lower than expected.\n");
+	}
+
 	igt_require_f(igt_wait(xe_gt_is_in_c6(xe, gt), 1000, 10), "GT %d should be in C6\n", gt);
 
 	/* While idle check full RC6. */
diff --git a/tests/meson.build b/tests/meson.build
index 26d9345ec..e682ed9dd 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -425,6 +425,7 @@ extra_dependencies = {
 	'sw_sync': [ libatomic ],
 	'xe_fault_injection': [ lib_igt_xe_oa ],
 	'xe_oa': [ lib_igt_xe_oa ],
+	'xe_pmu': [ lib_igt_drm_clients ],
         'xe_compute': [ igt_deps,lib_igt_perf,lib_igt_profiling,math ],
 }
 
-- 
2.34.1