[PATCH 4/7] drm/vblank: timer: Reorganize get_vblank_timeout

[Thomas Zimmermann <tzimmermann@suse.de>]

Handle vblank->enabled in a separate branch before handling the
opposite case. Prepares the code for estimating the vblank timeout
while vblanking is disabled. No functional changes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_vblank.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 03b07e3c2598..cecaef98aa52 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -2306,8 +2306,6 @@ bool drm_crtc_vblank_get_vblank_timeout(struct drm_crtc *crtc, ktime_t *vblank_t
 	struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc);
 	struct drm_vblank_crtc_timer *vtimer = &vblank->vblank_timer;
 	const struct drm_display_mode *mode;
-	u64 cur_count;
-	ktime_t cur_time;
 	s64 framedur_ns;
 	s64 activedur_ns;
 
@@ -2316,24 +2314,28 @@ bool drm_crtc_vblank_get_vblank_timeout(struct drm_crtc *crtc, ktime_t *vblank_t
 	else
 		mode = &crtc->hwmode;
 
-	if (!READ_ONCE(vblank->enabled))
-		return false;
+	if (READ_ONCE(vblank->enabled)) {
+		ktime_t cur_time;
+		u64 cur_count;
 
-	/*
-	 * A concurrent vblank timeout could update the expires field before
-	 * we compare it with the vblank time. Hence we'd compare the old
-	 * expiry time to the new vblank time; deducing the timer had already
-	 * expired. Reread until we get consistent values from both fields.
-	 */
-	do {
-		cur_count = drm_crtc_vblank_count_and_time(crtc, &cur_time);
-		*vblank_time = READ_ONCE(vtimer->timer.node.expires);
-	} while (cur_count != drm_crtc_vblank_count_and_time(crtc, &cur_time));
+		/*
+		 * A concurrent vblank timeout could update the expires field before
+		 * we compare it with the vblank time. Hence we'd compare the old
+		 * expiry time to the new vblank time; deducing the timer had already
+		 * expired. Reread until we get consistent values from both fields.
+		 */
+		do {
+			cur_count = drm_crtc_vblank_count_and_time(crtc, &cur_time);
+			*vblank_time = READ_ONCE(vtimer->timer.node.expires);
+		} while (cur_count != drm_crtc_vblank_count_and_time(crtc, &cur_time));
 
-	if (drm_WARN_ON(dev, !ktime_compare(*vblank_time, cur_time)))
-		return false; /* Already expired */
+		if (drm_WARN_ON(dev, !ktime_compare(*vblank_time, cur_time)))
+			return false; /* already expired */
 
-	framedur_ns = vblank->framedur_ns;
+		framedur_ns = vblank->framedur_ns;
+	} else {
+		return false;
+	}
 
 	/*
 	 * To prevent races we rolled the hrtimer forward before we did any
-- 
2.54.0