drm/exynos: dsi: Add support for panel prepare and unprepare routines

Modify exynos_dsi driver to support the new panel calls:
prepare and unprepare.
Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Acked-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/exynos/exynos_drm_dsi.c

@@ -1115,7 +1115,7 @@ static int exynos_dsi_enable(struct exynos_dsi *dsi)
 	if (ret < 0)
 		return ret;
 
-	ret = drm_panel_enable(dsi->panel);
+	ret = drm_panel_prepare(dsi->panel);
 	if (ret < 0) {
 		exynos_dsi_poweroff(dsi);
 		return ret;
@@ -1124,6 +1124,14 @@ static int exynos_dsi_enable(struct exynos_dsi *dsi)
 	exynos_dsi_set_display_mode(dsi);
 	exynos_dsi_set_display_enable(dsi, true);
 
+	ret = drm_panel_enable(dsi->panel);
+	if (ret < 0) {
+		exynos_dsi_set_display_enable(dsi, false);
+		drm_panel_unprepare(dsi->panel);
+		exynos_dsi_poweroff(dsi);
+		return ret;
+	}
+
 	dsi->state |= DSIM_STATE_ENABLED;
 
 	return 0;
@@ -1134,8 +1142,9 @@ static void exynos_dsi_disable(struct exynos_dsi *dsi)
 	if (!(dsi->state & DSIM_STATE_ENABLED))
 		return;
 
-	exynos_dsi_set_display_enable(dsi, false);
 	drm_panel_disable(dsi->panel);
+	exynos_dsi_set_display_enable(dsi, false);
+	drm_panel_unprepare(dsi->panel);
 	exynos_dsi_poweroff(dsi);
 
 	dsi->state &= ~DSIM_STATE_ENABLED;