DRM: ingenic: Add support for panels with 8-bit serial bus

Add support for the LCD panels with a serial 8-bit bus, where the color
components of each 24-bit pixel are sent sequentially.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190627182114.27299-3-paul@crapouillou.net
# *** extracted tags ***
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>

drivers/gpu/drm/ingenic/ingenic-drm.c

@@ -426,6 +426,9 @@ static void ingenic_drm_encoder_atomic_mode_set(struct drm_encoder *encoder,
 			case MEDIA_BUS_FMT_RGB888_1X24:
 				cfg |= JZ_LCD_CFG_MODE_GENERIC_24BIT;
 				break;
+			case MEDIA_BUS_FMT_RGB888_3X8:
+				cfg |= JZ_LCD_CFG_MODE_8BIT_SERIAL;
+				break;
 			default:
 				break;
 			}
@@ -451,6 +454,7 @@ static int ingenic_drm_encoder_atomic_check(struct drm_encoder *encoder,
 	case MEDIA_BUS_FMT_RGB565_1X16:
 	case MEDIA_BUS_FMT_RGB666_1X18:
 	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_RGB888_3X8:
 		return 0;
 	default:
 		return -EINVAL;