diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 290f328c6a42..0d96264ec5c6 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -71,8 +71,8 @@
 #define DSI_PS_WC			0x3fff
 #define DSI_PS_SEL			(3 << 16)
 #define PACKED_PS_16BIT_RGB565		(0 << 16)
-#define LOOSELY_PS_18BIT_RGB666		(1 << 16)
-#define PACKED_PS_18BIT_RGB666		(2 << 16)
+#define PACKED_PS_18BIT_RGB666		(1 << 16)
+#define LOOSELY_PS_24BIT_RGB666		(2 << 16)
 #define PACKED_PS_24BIT_RGB888		(3 << 16)
 
 #define DSI_VSA_NL		0x20
@@ -367,10 +367,10 @@ static void mtk_dsi_ps_control_vact(struct mtk_dsi *dsi)
 		ps_bpp_mode |= PACKED_PS_24BIT_RGB888;
 		break;
 	case MIPI_DSI_FMT_RGB666:
-		ps_bpp_mode |= PACKED_PS_18BIT_RGB666;
+		ps_bpp_mode |= LOOSELY_PS_24BIT_RGB666;
 		break;
 	case MIPI_DSI_FMT_RGB666_PACKED:
-		ps_bpp_mode |= LOOSELY_PS_18BIT_RGB666;
+		ps_bpp_mode |= PACKED_PS_18BIT_RGB666;
 		break;
 	case MIPI_DSI_FMT_RGB565:
 		ps_bpp_mode |= PACKED_PS_16BIT_RGB565;
@@ -424,7 +424,7 @@ static void mtk_dsi_ps_control(struct mtk_dsi *dsi)
 		dsi_tmp_buf_bpp = 3;
 		break;
 	case MIPI_DSI_FMT_RGB666:
-		tmp_reg = LOOSELY_PS_18BIT_RGB666;
+		tmp_reg = LOOSELY_PS_24BIT_RGB666;
 		dsi_tmp_buf_bpp = 3;
 		break;
 	case MIPI_DSI_FMT_RGB666_PACKED: