diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 2854399856ba..c22206b6bc85 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -210,18 +210,12 @@ static int ast_detect_chip(struct drm_device *dev, bool *need_post)
 	ast->tx_chip_type = AST_TX_NONE;
 
 	/*
-	 * VGACRA3 Enhanced Color Mode Register, check if DVO is already
-	 * enabled, in that case, assume we have a SIL164 TMDS transmitter
-	 *
-	 * Don't make that assumption if we the chip wasn't enabled and
-	 * is at power-on reset, otherwise we'll incorrectly "detect" a
-	 * SIL164 when there is none.
+	 * VGACRA3 Enhanced Color Mode Register, unconditionally enable
+	 * DVO output on Blackbird systems and set SIL164 chip type as
+	 * interim solution pending proper ITE driver.
 	 */
-	if (!*need_post) {
-		jreg = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xa3, 0xff);
-		if (jreg & 0x80)
-			ast->tx_chip_type = AST_TX_SIL164;
-	}
+	ast_set_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xa3, 0xff, 0x80);
+	ast->tx_chip_type = AST_TX_SIL164;
 
 	if ((ast->chip == AST2300) || (ast->chip == AST2400)) {
 		/*