drm/tegra: dc: Disable plane if it is invisible

On Tegra20 if plane has width or height equal to 0, it will be infinitely
wide or tall. Let's disable the plane if it is invisible on atomic state
committing to fix the issue. The Rockchip DRM driver does the same.
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Reviewed-by: NErik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/dc.c

@@ -559,6 +559,23 @@ static int tegra_plane_atomic_check(struct drm_plane *plane,
 	return 0;
 }
 
+static void tegra_dc_disable_window(struct tegra_dc *dc, int index)
+{
+	unsigned long flags;
+	u32 value;
+
+	spin_lock_irqsave(&dc->lock, flags);
+
+	value = WINDOW_A_SELECT << index;
+	tegra_dc_writel(dc, value, DC_CMD_DISPLAY_WINDOW_HEADER);
+
+	value = tegra_dc_readl(dc, DC_WIN_WIN_OPTIONS);
+	value &= ~WIN_ENABLE;
+	tegra_dc_writel(dc, value, DC_WIN_WIN_OPTIONS);
+
+	spin_unlock_irqrestore(&dc->lock, flags);
+}
+
 static void tegra_plane_atomic_update(struct drm_plane *plane,
 				      struct drm_plane_state *old_state)
 {
@@ -573,6 +590,9 @@ static void tegra_plane_atomic_update(struct drm_plane *plane,
 	if (!plane->state->crtc || !plane->state->fb)
 		return;
 
+	if (!plane->state->visible)
+		return tegra_dc_disable_window(dc, p->index);
+
 	memset(&window, 0, sizeof(window));
 	window.src.x = plane->state->src.x1 >> 16;
 	window.src.y = plane->state->src.y1 >> 16;
@@ -612,8 +632,6 @@ static void tegra_plane_atomic_disable(struct drm_plane *plane,
 {
 	struct tegra_plane *p = to_tegra_plane(plane);
 	struct tegra_dc *dc;
-	unsigned long flags;
-	u32 value;
 
 	/* rien ne va plus */
 	if (!old_state || !old_state->crtc)
@@ -621,16 +639,7 @@ static void tegra_plane_atomic_disable(struct drm_plane *plane,
 
 	dc = to_tegra_dc(old_state->crtc);
 
-	spin_lock_irqsave(&dc->lock, flags);
-
-	value = WINDOW_A_SELECT << p->index;
-	tegra_dc_writel(dc, value, DC_CMD_DISPLAY_WINDOW_HEADER);
-
-	value = tegra_dc_readl(dc, DC_WIN_WIN_OPTIONS);
-	value &= ~WIN_ENABLE;
-	tegra_dc_writel(dc, value, DC_WIN_WIN_OPTIONS);
-
-	spin_unlock_irqrestore(&dc->lock, flags);
+	tegra_dc_disable_window(dc, p->index);
 }
 
 static const struct drm_plane_helper_funcs tegra_primary_plane_helper_funcs = {