drm/hisilicon: Set preferred mode resolution and maximum resolution

set the preferred mode resolution to 1024 * 768 and maximum
resolution to 1920 * 1200.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Gong junjie <gongjunjie2@huawei.com>
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1582080707-18825-1-git-send-email-tiantao6@hisilicon.com

drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c

@@ -11,16 +11,25 @@
  *	Jianhua Li <lijianhua@huawei.com>
  */
 
+#include <drm/drm_gem_vram_helper.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_print.h>
 
 #include "hibmc_drm_drv.h"
 #include "hibmc_drm_regs.h"
 
 static int hibmc_connector_get_modes(struct drm_connector *connector)
 {
-	return drm_add_modes_noedid(connector, 800, 600);
+	int count;
+
+	count = drm_add_modes_noedid(connector,
+				     connector->dev->mode_config.max_width,
+				     connector->dev->mode_config.max_height);
+	drm_set_preferred_mode(connector, 1024, 768);
+
+	return count;
 }
 
 static enum drm_mode_status hibmc_connector_mode_valid(struct drm_connector *connector,