drm/stm: ltdc: reset controller to avoid partial refresh

Display controller reset must be done as soon as possible after enable
the clock to avoid partial refresh on screen.
Signed-off-by: Yannick Fertré <yannick.fertre@st.com>
Acked-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1554283453-2879-1-git-send-email-yannick.fertre@st.com

drivers/gpu/drm/stm/ltdc.c

@@ -1137,6 +1137,12 @@ int ltdc_load(struct drm_device *ddev)
 		return -ENODEV;
 	}
 
+	if (!IS_ERR(rstc)) {
+		reset_control_assert(rstc);
+		usleep_range(10, 20);
+		reset_control_deassert(rstc);
+	}
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	ldev->regs = devm_ioremap_resource(dev, res);
 	if (IS_ERR(ldev->regs)) {
@@ -1163,11 +1169,6 @@ int ltdc_load(struct drm_device *ddev)
 		}
 	}
 
-	if (!IS_ERR(rstc)) {
-		reset_control_assert(rstc);
-		usleep_range(10, 20);
-		reset_control_deassert(rstc);
-	}
 
 	ret = ltdc_get_caps(ddev);
 	if (ret) {