linux-kernel - [PATCH v4 10/14] drm/vblank: Add helper to get next vblank time

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Message-Id: <20230218211608.1630586-11-robdclark@gmail.com>
Date:   Sat, 18 Feb 2023 13:15:53 -0800
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, Daniel Vetter <daniel@...ll.ch>,
        Christian König 
        <ckoenig.leichtzumerken@...il.com>,
        Michel Dänzer <michel@...nzer.net>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Alex Deucher <alexander.deucher@....com>,
        Pekka Paalanen <ppaalanen@...il.com>,
        Simon Ser <contact@...rsion.fr>,
        Rob Clark <robdclark@...omium.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v4 10/14] drm/vblank: Add helper to get next vblank time

From: Rob Clark <robdclark@...omium.org>

Will be used in the next commit to set a deadline on fences that an
atomic update is waiting on.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/drm_vblank.c | 32 ++++++++++++++++++++++++++++++++
 include/drm/drm_vblank.h     |  1 +
 2 files changed, 33 insertions(+)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 2ff31717a3de..caf25ebb34c5 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -980,6 +980,38 @@ u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
 }
 EXPORT_SYMBOL(drm_crtc_vblank_count_and_time);
 
+/**
+ * drm_crtc_next_vblank_time - calculate the time of the next vblank
+ * @crtc: the crtc for which to calculate next vblank time
+ * @vblanktime: pointer to time to receive the next vblank timestamp.
+ *
+ * Calculate the expected time of the next vblank based on time of previous
+ * vblank and frame duration
+ */
+int drm_crtc_next_vblank_time(struct drm_crtc *crtc, ktime_t *vblanktime)
+{
+	unsigned int pipe = drm_crtc_index(crtc);
+	struct drm_vblank_crtc *vblank = &crtc->dev->vblank[pipe];
+	u64 count;
+
+	if (!vblank->framedur_ns)
+		return -EINVAL;
+
+	count = drm_vblank_count_and_time(crtc->dev, pipe, vblanktime);
+
+	/*
+	 * If we don't get a valid count, then we probably also don't
+	 * have a valid time:
+	 */
+	if (!count)
+		return -EINVAL;
+
+	*vblanktime = ktime_add(*vblanktime, ns_to_ktime(vblank->framedur_ns));
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_crtc_next_vblank_time);
+
 static void send_vblank_event(struct drm_device *dev,
 		struct drm_pending_vblank_event *e,
 		u64 seq, ktime_t now)
diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h
index 733a3e2d1d10..a63bc2c92f3c 100644
--- a/include/drm/drm_vblank.h
+++ b/include/drm/drm_vblank.h
@@ -230,6 +230,7 @@ bool drm_dev_has_vblank(const struct drm_device *dev);
 u64 drm_crtc_vblank_count(struct drm_crtc *crtc);
 u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
 				   ktime_t *vblanktime);
+int drm_crtc_next_vblank_time(struct drm_crtc *crtc, ktime_t *vblanktime);
 void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
 			       struct drm_pending_vblank_event *e);
 void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
-- 
2.39.1