overlay: read rc6 status from perf

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

overlay/overlay.c

@@ -582,28 +582,31 @@ static void show_gpu_freq(struct overlay_context *ctx, struct overlay_gpu_freq *
 		len = sprintf(buf, "RC6: %d%%", gf->rc6.rc6_combined);
 		cairo_set_source_rgba(ctx->cr, 1, 1, 1, 1);
 		cairo_move_to(ctx->cr, PAD, y);
-		if (gf->rc6.rc6_combined && !is_power_of_two(gf->rc6.enabled)) {
+		if (gf->rc6.rc6_combined) {
 			int need_comma = 0;
+			int rewind = len;
 			len += sprintf(buf + len, " (");
-			if (gf->rc6.enabled & 1) {
+			if (gf->rc6.rc6) {
 				len += sprintf(buf + len, "%src6=%d%%",
 					       need_comma ? ", " : "",
 					       gf->rc6.rc6);
-				need_comma = 1;
+				need_comma++;
 			}
-			if (gf->rc6.enabled & 2) {
+			if (gf->rc6.rc6p) {
 				len += sprintf(buf + len, "%src6p=%d%%",
 					       need_comma ? ", " : "",
 					       gf->rc6.rc6p);
-				need_comma = 1;
+				need_comma++;
 			}
-			if (gf->rc6.enabled & 4) {
+			if (gf->rc6.rc6pp) {
 				len += sprintf(buf + len, "%src6pp=%d%%",
 					       need_comma ? ", " : "",
 					       gf->rc6.rc6pp);
-				need_comma = 1;
+				need_comma++;
 			}
 			sprintf(buf + len, ")");
+			if (need_comma <= 1)
+				buf[rewind] = '\0';
 		}
 		cairo_show_text(ctx->cr, buf);
 		y += 14;

overlay/perf.h

@@ -35,6 +35,10 @@
 #define I915_PERF_ENERGY 34
 #define I915_PERF_INTERRUPTS 35
 
+#define I915_PERF_RC6_RESIDENCY		40
+#define I915_PERF_RC6p_RESIDENCY	41
+#define I915_PERF_RC6pp_RESIDENCY	42
+
 static inline int
 perf_event_open(struct perf_event_attr *attr,
 		pid_t pid,

overlay/rc6.c

@@ -32,17 +32,58 @@
 #include <errno.h>
 
 #include "rc6.h"
+#include "perf.h"
+
+static int perf_i915_open(int config, int group)
+{
+	struct perf_event_attr attr;
+
+	memset(&attr, 0, sizeof (attr));
+
+	attr.type = i915_type_id();
+	if (attr.type == 0)
+		return -ENOENT;
+	attr.config = config;
+
+	attr.read_format = PERF_FORMAT_TOTAL_TIME_ENABLED;
+	if (group == -1)
+		attr.read_format |= PERF_FORMAT_GROUP;
+
+	return perf_event_open(&attr, -1, 0, group, 0);
+}
+
+#define RC6	(1<<0)
+#define RC6p	(1<<1)
+#define RC6pp	(1<<2)
+
+static int perf_open(unsigned *flags)
+{
+	int fd;
+
+	fd = perf_i915_open(I915_PERF_RC6_RESIDENCY, -1);
+	if (fd < 0)
+		return -1;
+
+	*flags |= RC6;
+	if (perf_i915_open(I915_PERF_RC6p_RESIDENCY, fd) >= 0)
+		*flags |= RC6p;
+
+	if (perf_i915_open(I915_PERF_RC6pp_RESIDENCY, fd) >= 0)
+		*flags |= RC6pp;
+
+	return fd;
+}
 
 int rc6_init(struct rc6 *rc6)
 {
-	struct stat st;
-	int fd;
-
 	memset(rc6, 0, sizeof(*rc6));
 
-	fd = stat("/sys/class/drm/card0/power", &st);
-	if (fd == -1)
-		return rc6->error = errno;
+	rc6->fd = perf_open(&rc6->flags);
+	if (rc6->fd == -1) {
+		struct stat st;
+		if (stat("/sys/class/drm/card0/power", &st) < 0)
+			return rc6->error = errno;
+	}
 
 	return 0;
 }
@@ -54,13 +95,13 @@ static uint64_t file_to_u64(const char *path)
 
 	fd = open(path, 0);
 	if (fd < 0)
-		return 0;
+		return -1;
 
 	len = read(fd, buf, sizeof(buf)-1);
 	close(fd);
 
 	if (len < 0)
-		return 0;
+		return -1;
 
 	buf[len] = '\0';
 
@@ -82,37 +123,57 @@ int rc6_update(struct rc6 *rc6)
 	struct rc6_stat *s = &rc6->stat[rc6->count++&1];
 	struct rc6_stat *d = &rc6->stat[rc6->count&1];
 	uint64_t d_time, d_rc6, d_rc6p, d_rc6pp;
-	struct stat st;
 
 	if (rc6->error)
 		return rc6->error;
 
-	if (stat("/sys/class/drm/card0/power/rc6_residency_ms", &st) < 0)
-		return rc6->error = ENOENT;
+	if (rc6->fd == -1) {
+		struct stat st;
 
-	rc6->enabled = file_to_u64("/sys/class/drm/card0/power/rc6_enable");
-	if (rc6->enabled == 0)
-		return EAGAIN;
+		if (stat("/sys/class/drm/card0/power/rc6_residency_ms", &st) < 0)
+			return rc6->error = ENOENT;
 
-	s->rc6_residency = file_to_u64("/sys/class/drm/card0/power/rc6_residency_ms");
-	s->rc6p_residency = file_to_u64("/sys/class/drm/card0/power/rc6p_residency_ms");
-	s->rc6pp_residency = file_to_u64("/sys/class/drm/card0/power/rc6pp_residency_ms");
-	s->timestamp = clock_ms_to_u64();
+		s->rc6_residency = file_to_u64("/sys/class/drm/card0/power/rc6_residency_ms");
+		s->rc6p_residency = file_to_u64("/sys/class/drm/card0/power/rc6p_residency_ms");
+		s->rc6pp_residency = file_to_u64("/sys/class/drm/card0/power/rc6pp_residency_ms");
+		s->timestamp = clock_ms_to_u64();
+	} else {
+		uint64_t data[5];
+		int len;
+
+		len = read(rc6->fd, data, sizeof(data));
+		if (len < 0)
+			return rc6->error = errno;
+
+		s->timestamp = data[1] / (1000*1000);
+
+		len = 2;
+		if (rc6->flags & RC6)
+			s->rc6_residency = data[len++];
+		if (rc6->flags & RC6p)
+			s->rc6p_residency = data[len++];
+		if (rc6->flags & RC6pp)
+			s->rc6pp_residency = data[len++];
+	}
 
 	if (rc6->count == 1)
 		return EAGAIN;
 
 	d_time = s->timestamp - d->timestamp;
+	if (d_time == 0) {
+		rc6->count--;
+		return EAGAIN;
+	}
 
 	d_rc6 = s->rc6_residency - d->rc6_residency;
-	rc6->rc6 = 100 * d_rc6 / d_time;
+	rc6->rc6 = (100 * d_rc6 + d_time/2) / d_time;
 
 	d_rc6p = s->rc6p_residency - d->rc6p_residency;
-	rc6->rc6p = 100 * d_rc6p / d_time;
+	rc6->rc6p = (100 * d_rc6p + d_time/2) / d_time;
 
 	d_rc6pp = s->rc6pp_residency - d->rc6pp_residency;
-	rc6->rc6pp = 100 * d_rc6pp / d_time;
+	rc6->rc6pp = (100 * d_rc6pp + d_time/2) / d_time;
 
-	rc6->rc6_combined = 100 * (d_rc6 + d_rc6p + d_rc6pp) / d_time;
+	rc6->rc6_combined = (100 * (d_rc6 + d_rc6p + d_rc6pp) + d_time/2) / d_time;
 	return 0;
 }

overlay/rc6.h

@@ -35,10 +35,11 @@ struct rc6 {
 		uint64_t timestamp;
 	} stat[2];
 
+	int fd;
 	int count;
 	int error;
 
-	unsigned enabled;
+	unsigned flags;
 
 	uint8_t rc6;
 	uint8_t rc6p;