drm/vc4: hvs: Move the dlist setup to its own function

The vc4_hvs_update_dlist function mostly deals with setting up the
vblank events and setting up the dlist entry pointer to our current
active one.

We'll want to do the former separately from the vblank handling in later
patches, so let's move it to a function of its own.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20220331143744.777652-6-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_hvs.c

@@ -382,10 +382,19 @@ int vc4_hvs_atomic_check(struct drm_crtc *crtc, struct drm_atomic_state *state)
 	return 0;
 }
 
-static void vc4_hvs_update_dlist(struct drm_crtc *crtc)
+static void vc4_hvs_install_dlist(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
 	struct vc4_dev *vc4 = to_vc4_dev(dev);
+	struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc->state);
+
+	HVS_WRITE(SCALER_DISPLISTX(vc4_state->assigned_channel),
+		  vc4_state->mm.start);
+}
+
+static void vc4_hvs_update_dlist(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
 	struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
 	struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc->state);
 	unsigned long flags;
@@ -405,9 +414,6 @@ static void vc4_hvs_update_dlist(struct drm_crtc *crtc)
 		spin_unlock_irqrestore(&dev->event_lock, flags);
 	}
 
-	HVS_WRITE(SCALER_DISPLISTX(vc4_state->assigned_channel),
-		  vc4_state->mm.start);
-
 	spin_lock_irqsave(&vc4_crtc->irq_lock, flags);
 	vc4_crtc->current_dlist = vc4_state->mm.start;
 	spin_unlock_irqrestore(&vc4_crtc->irq_lock, flags);
@@ -434,6 +440,7 @@ void vc4_hvs_atomic_enable(struct drm_crtc *crtc,
 	struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
 	bool oneshot = vc4_crtc->feeds_txp;
 
+	vc4_hvs_install_dlist(crtc);
 	vc4_hvs_update_dlist(crtc);
 	vc4_hvs_init_channel(vc4, crtc, mode, oneshot);
 }
@@ -509,8 +516,10 @@ void vc4_hvs_atomic_flush(struct drm_crtc *crtc,
 	 * If the CRTC is being disabled, there's no point in updating this
 	 * information.
 	 */
-	if (crtc->state->active && old_state->active)
+	if (crtc->state->active && old_state->active) {
+		vc4_hvs_install_dlist(crtc);
 		vc4_hvs_update_dlist(crtc);
+	}
 
 	if (crtc->state->color_mgmt_changed) {
 		u32 dispbkgndx = HVS_READ(SCALER_DISPBKGNDX(channel));