tests/pm_rps: vlv: wait for freq to settle

At least on VLV when forcing a new GT frequency by writing to the
min/max freq sysfs entries the kernel doesn't wait until the new
frequency settles, so the subsequent readback check might fail. To fix
this wait until the current frequency is between the min/max values
using a 10ms timeout.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Imre Deak <imre.deak@intel.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/tests/pm_rps.c b/tests/pm_rps.c
index 101f65d8..4429b2c5 100644
--- a/tests/pm_rps.c
+++ b/tests/pm_rps.c
@@ -34,6 +34,7 @@
 #include <fcntl.h>
 #include <signal.h>
 #include <errno.h>
+#include <time.h>
 #include <sys/wait.h>
 
 #include "drmtest.h"
@@ -87,6 +88,38 @@ static void read_freqs(int *freqs)
 		freqs[i] = readval(stuff[i].filp);
 }
 
+static void nsleep(unsigned long ns)
+{
+	struct timespec ts;
+	int ret;
+
+	ts.tv_sec = 0;
+	ts.tv_nsec = ns;
+	do {
+		struct timespec rem;
+
+		ret = nanosleep(&ts, &rem);
+		igt_assert(ret == 0 || errno == EINTR);
+		ts = rem;
+	} while (ret && errno == EINTR);
+}
+
+static void wait_freq_settle(void)
+{
+	int timeout = 10;
+
+	while (1) {
+		int freqs[NUMFREQ];
+
+		read_freqs(freqs);
+		if (freqs[CUR] >= freqs[MIN] && freqs[CUR] <= freqs[MAX])
+			break;
+		nsleep(1000000);
+		if (!timeout--)
+			break;
+	}
+}
+
 static int do_writeval(FILE *filp, int val, int lerrno)
 {
 	int ret, orig;
@@ -102,6 +135,7 @@ static int do_writeval(FILE *filp, int val, int lerrno)
 	} else {
 		/* Expecting no error */
 		igt_assert_neq(ret, 0);
+		wait_freq_settle();
 		igt_assert(readval(filp) == val);
 	}