3 files changed, 31 insertions, 5 deletions

diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 23dd97506f28..e77bd8b57df2 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -287,6 +287,9 @@ int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
 		req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0;
 		req->value |= dev->driver->prime_handle_to_fd ? DRM_PRIME_CAP_EXPORT : 0;
 		break;
+	case DRM_CAP_TIMESTAMP_MONOTONIC:
+		req->value = drm_timestamp_monotonic;
+		break;
 	default:
 		return -EINVAL;
 	}
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index ef5b5f70735e..c0f0046d8078 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -633,7 +633,8 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 
 		/* Get system timestamp after query. */
 		etime = ktime_get();
-		mono_time_offset = ktime_get_monotonic_offset();
+		if (!drm_timestamp_monotonic)
+			mono_time_offset = ktime_get_monotonic_offset();
 
 		preempt_enable();
 
@@ -691,7 +692,9 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 		vbl_status |= 0x8;
 	}
 
-	etime = ktime_sub(etime, mono_time_offset);
+	if (!drm_timestamp_monotonic)
+		etime = ktime_sub(etime, mono_time_offset);
+
 	/* save this only for debugging purposes */
 	tv_etime = ktime_to_timeval(etime);
 	/* Subtract time delta from raw timestamp to get final
@@ -714,6 +717,17 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 }
 EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos);
 
+static struct timeval get_drm_timestamp(void)
+{
+	ktime_t now;
+
+	now = ktime_get();
+	if (!drm_timestamp_monotonic)
+		now = ktime_sub(now, ktime_get_monotonic_offset());
+
+	return ktime_to_timeval(now);
+}
+
 /**
  * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
  * vblank interval.
@@ -751,9 +765,9 @@ u32 drm_get_last_vbltimestamp(struct drm_device *dev, int crtc,
 	}
 
 	/* GPU high precision timestamp query unsupported or failed.
-	 * Return gettimeofday timestamp as best estimate.
+	 * Return current monotonic/gettimeofday timestamp as best estimate.
 	 */
-	do_gettimeofday(tvblank);
+	*tvblank = get_drm_timestamp();
 
 	return 0;
 }
@@ -842,7 +856,8 @@ void drm_send_vblank_event(struct drm_device *dev, int crtc,
 		seq = drm_vblank_count_and_time(dev, crtc, &now);
 	} else {
 		seq = 0;
-		do_gettimeofday(&now);
+
+		now = get_drm_timestamp();
 	}
 	send_vblank_event(dev, e, seq, &now);
 }
diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index 6fcdd8ebcb3d..200e104f1fa0 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -46,16 +46,24 @@ EXPORT_SYMBOL(drm_vblank_offdelay);
 unsigned int drm_timestamp_precision = 20;  /* Default to 20 usecs. */
 EXPORT_SYMBOL(drm_timestamp_precision);
 
+/*
+ * Default to use monotonic timestamps for wait-for-vblank and page-flip
+ * complete events.
+ */
+unsigned int drm_timestamp_monotonic = 1;
+
 MODULE_AUTHOR(CORE_AUTHOR);
 MODULE_DESCRIPTION(CORE_DESC);
 MODULE_LICENSE("GPL and additional rights");
 MODULE_PARM_DESC(debug, "Enable debug output");
 MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]");
 MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
+MODULE_PARM_DESC(timestamp_monotonic, "Use monotonic timestamps");
 
 module_param_named(debug, drm_debug, int, 0600);
 module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
 module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
+module_param_named(timestamp_monotonic, drm_timestamp_monotonic, int, 0600);
 
 struct idr drm_minors_idr;