drm/panel-simple: Read panel orientation

The panel orientation needs to parsed from a device-tree and assigned to
the panel's connector in order to make orientation property available to
userspace. That's what this patch does for the panel-simple driver.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200813215609.28643-5-digetx@gmail.com

drivers/gpu/drm/panel/panel-simple.c

@@ -112,6 +112,8 @@ struct panel_simple {
 	struct gpio_desc *hpd_gpio;
 
 	struct drm_display_mode override_mode;
+
+	enum drm_panel_orientation orientation;
 };
 
 static inline struct panel_simple *to_panel_simple(struct drm_panel *panel)
@@ -371,6 +373,9 @@ static int panel_simple_get_modes(struct drm_panel *panel,
 	/* add hard-coded panel modes */
 	num += panel_simple_get_non_edid_modes(p, connector);
 
+	/* set up connector's "panel orientation" property */
+	drm_connector_set_panel_orientation(connector, p->orientation);
+
 	return num;
 }
 
@@ -532,6 +537,12 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 		return err;
 	}
 
+	err = of_drm_get_panel_orientation(dev->of_node, &panel->orientation);
+	if (err) {
+		dev_err(dev, "%pOF: failed to get orientation %d\n", dev->of_node, err);
+		return err;
+	}
+
 	ddc = of_parse_phandle(dev->of_node, "ddc-i2c-bus", 0);
 	if (ddc) {
 		panel->ddc = of_find_i2c_adapter_by_node(ddc);