sunxi: video: Fallback from HDMI to VGA on boards with VGA

If a board has no LCD, but does have VGA fallback to VGA when no HDMI cable
is connected (unless hpd=0).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

doc/README.video

@@ -50,8 +50,7 @@ The sunxi u-boot driver supports the following video-mode options:
 
 - hpd=[0|1] - Enable use of the hdmi HotPlug Detect feature
  0: Disabled. Configure dvi/hdmi output even if no cable is detected
- 1: Enabled. If a LCD has been configured fallback to the LCD when no cable is
-    detected, if no LCD is configured, disable video ouput.
+ 1: Enabled.  Fallback to the lcd / vga / none in that order (if available)
  Defaults to hpd=1.
 
 - edid=[0|1] - Enable use of DDC + EDID to get monitor info

drivers/video/sunxi_display.c

@@ -846,36 +846,43 @@ void *video_hw_init(void)
 		printf("Unknown monitor: '%s', falling back to '%s'\n",
 		       mon, sunxi_get_mon_desc(sunxi_display.monitor));
 
+#ifdef CONFIG_VIDEO_HDMI
+	/* If HDMI/DVI is selected do HPD & EDID, and handle fallback */
+	if (sunxi_display.monitor == sunxi_monitor_dvi ||
+	    sunxi_display.monitor == sunxi_monitor_hdmi) {
+		/* Always call hdp_detect, as it also enables clocks, etc. */
+		ret = sunxi_hdmi_hpd_detect();
+		if (ret) {
+			printf("HDMI connected: ");
+			if (edid && sunxi_hdmi_edid_get_mode(&custom) == 0)
+				mode = &custom;
+		} else if (hpd) {
+			sunxi_hdmi_shutdown();
+			/* Fallback to lcd / vga / none */
+			if (lcd_mode[0]) {
+				sunxi_display.monitor = sunxi_monitor_lcd;
+			} else {
+#ifdef CONFIG_VIDEO_VGA_VIA_LCD
+				sunxi_display.monitor = sunxi_monitor_vga;
+#else
+				sunxi_display.monitor = sunxi_monitor_none;
+#endif
+			}
+		} /* else continue with hdmi/dvi without a cable connected */
+	}
+#endif
+
 	switch (sunxi_display.monitor) {
 	case sunxi_monitor_none:
 		return NULL;
 	case sunxi_monitor_dvi:
 	case sunxi_monitor_hdmi:
-#ifndef CONFIG_VIDEO_HDMI
+#ifdef CONFIG_VIDEO_HDMI
+		break;
+#else
 		printf("HDMI/DVI not supported on this board\n");
 		sunxi_display.monitor = sunxi_monitor_none;
 		return NULL;
-#else
-		/* Always call hdp_detect, as it also enables clocks, etc. */
-		ret = sunxi_hdmi_hpd_detect();
-		if (ret) {
-			printf("HDMI connected: ");
-			if (edid && sunxi_hdmi_edid_get_mode(&custom) == 0)
-				mode = &custom;
-			break;
-		}
-		if (!hpd)
-			break; /* User has requested to ignore hpd */
-
-		sunxi_hdmi_shutdown();
-
-		if (lcd_mode[0] == 0) {
-			sunxi_display.monitor = sunxi_monitor_none;
-			return NULL; /* No LCD, bail */
-		}
-
-		/* Fall back / through to LCD */
-		sunxi_display.monitor = sunxi_monitor_lcd;
 #endif
 	case sunxi_monitor_lcd:
 		if (lcd_mode[0]) {