[PATCH 4/4] pm_rps: Require that cur reaches min at idle

[jeff.mcgee@intel.com]

From: Jeff McGee <jeff.mcgee@intel.com>

The current frequency should reach the minimum frequency within a
reasonable time during idle. We hold forcewake to prevent interference
from sleep states.

Signed-off-by: Jeff McGee <jeff.mcgee@intel.com>
---
 tests/pm_rps.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/tests/pm_rps.c b/tests/pm_rps.c
index 7ae0438..50c66ee 100644
--- a/tests/pm_rps.c
+++ b/tests/pm_rps.c
@@ -33,6 +33,7 @@
 #include <unistd.h>
 #include <getopt.h>
 #include "drmtest.h"
+#include "igt_debugfs.h"
 
 static bool verbose = false;
 
@@ -57,6 +58,9 @@ struct junk {
 	{ "cur", "r", NULL }, { "min", "rb+", NULL }, { "max", "rb+", NULL }, { "RP0", "r", NULL }, { "RP1", "r", NULL }, { "RPn", "r", NULL }, { NULL, NULL, NULL }
 };
 
+static igt_debugfs_t dfs;
+static FILE *forcewake;
+
 static int readval(FILE *filp)
 {
 	int val;
@@ -206,17 +210,33 @@ static void min_max_config(void (*check)(void))
 	check();
 }
 
+#define IDLE_WAIT_TIMESTEP_MSEC 100
+#define IDLE_WAIT_TIMEOUT_MSEC 3000
 static void idle_check(void)
 {
 	int freqs[NUMFREQ];
-
-	read_freqs(freqs);
-	dump(freqs);
-	checkit(freqs);
+	int wait = 0;
+
+	/* Monitor frequencies until cur settles down to min, which should
+	 * happen within the allotted time */
+	do {
+		read_freqs(freqs);
+		dump(freqs);
+		checkit(freqs);
+		if (freqs[CUR] == freqs[MIN])
+			break;
+		usleep(1000 * IDLE_WAIT_TIMESTEP_MSEC);
+		wait += IDLE_WAIT_TIMESTEP_MSEC;
+	} while (wait < IDLE_WAIT_TIMEOUT_MSEC);
+
+	igt_assert(freqs[CUR] == freqs[MIN]);
+	log("Required %d msec to reach cur=min\n", wait);
 }
 
 static void pm_rps_exit_handler(int sig)
 {
+	fclose(forcewake);
+
 	if (origfreqs[MIN] > readval(stuff[MAX].filp)) {
 		writeval(stuff[MAX].filp, origfreqs[MAX]);
 		writeval(stuff[MIN].filp, origfreqs[MIN]);
@@ -287,6 +307,12 @@ int main(int argc, char **argv)
 
 		read_freqs(origfreqs);
 
+		/* Hold forcewake throughout test to prevent sleep states from
+		 * interfering with evaluation of performance state management */
+		igt_require(igt_debugfs_init(&dfs) == 0);
+		forcewake = igt_debugfs_fopen(&dfs, "i915_forcewake_user", "r");
+		igt_require(forcewake);
+
 		igt_install_exit_handler(pm_rps_exit_handler);
 	}
 
-- 
1.8.5.2