[i-g-t 1/2] DO_NOT_MERGE: Disable C-states before stating the subtest

[Bhanuprakash Modem]

Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
---
 tests/kms_vrr.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tests/kms_vrr.c b/tests/kms_vrr.c
index 9de0ffc85..30ca85939 100644
--- a/tests/kms_vrr.c
+++ b/tests/kms_vrr.c
@@ -35,6 +35,7 @@
 #include "sw_sync.h"
 #include <fcntl.h>
 #include <signal.h>
+#include <limits.h>
 
 /**
  * SUBTEST: flip-basic
@@ -269,6 +270,26 @@ static void set_vrr_on_pipe(data_t *data, enum pipe pipe,
 						 NULL) == 0);
 }
 
+static void set_cstates(bool enable) {
+	char path[PATH_MAX];
+	FILE *file;
+	int num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+
+	for (int cpu = 0; cpu < num_cpus; cpu++) {
+		for (int state = 0; state < 9; state++) {
+			snprintf(path, PATH_MAX, "/sys/devices/system/cpu/cpu%d/cpuidle/state%d/disable", cpu, state);
+
+			file = fopen(path, "w");
+			if (!file)
+				continue;
+
+			rewind(file);
+			fprintf(file, "%s\n", enable? "1" : "0");
+			fclose(file);
+		}
+	}
+}
+
 /* Prepare the display for testing on the given pipe. */
 static void prepare_test(data_t *data, igt_output_t *output, enum pipe pipe)
 {
@@ -687,6 +708,9 @@ igt_main
 		igt_display_require(&data.display, data.drm_fd);
 		igt_require(data.display.is_atomic);
 		igt_display_require_output(&data.display);
+
+		if (is_intel_device(data.drm_fd))
+			set_cstates(false);
 	}
 
 	igt_describe("Tests that VRR is enabled and that the difference between flip "
@@ -731,6 +755,8 @@ igt_main
 	}
 
 	igt_fixture {
+		if (is_intel_device(data.drm_fd))
+			set_cstates(true);
 		igt_display_fini(&data.display);
 		drm_close_driver(data.drm_fd);
 	}
-- 
2.43.0