drm/imx: parallel-display: allow to determine bus format from the connected panel

Similarly to commit 5e501ed7 ("drm/imx: imx-ldb: allow to determine
bus format from the connected panel"), if a panel is connected to the ldb
output port via the of_graph bindings, the data mapping is determined from
the display_info.bus_format field provided by the panel instead of from the
optional interface_pix_fmt device tree property.
Reported-by: Ulrich Ölmann <u.oelmann@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Gary Bisson <gary.bisson@boundarydevices.com>

drivers/gpu/drm/imx/parallel-display.c

@@ -54,7 +54,11 @@ static int imx_pd_connector_get_modes(struct drm_connector *connector)
 
 	if (imxpd->panel && imxpd->panel->funcs &&
 	    imxpd->panel->funcs->get_modes) {
+		struct drm_display_info *di = &connector->display_info;
+
 		num_modes = imxpd->panel->funcs->get_modes(imxpd->panel);
+		if (!imxpd->bus_format && di->num_bus_formats)
+			imxpd->bus_format = di->bus_formats[0];
 		if (num_modes > 0)
 			return num_modes;
 	}