staging: xgifb: enable forcecrt2type on XG21

Make "forcecrt2type" to apply also for XG21. The patch enables user to
switch LVDS LCD ON/OFF without the need to update the video BIOS.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/xgifb/XGI_main_26.c

@@ -1744,17 +1744,16 @@ static void XGIfb_detect_VB(struct xgifb_video_info *xgifb_info)
 			XGIfb_crt1off = 0;
 	}
 
-	if (XGIfb_crt2type != -1)
-		/* TW: Override with option */
-		xgifb_info->display2 = XGIfb_crt2type;
-	else if (cr32 & XGI_VB_TV)
-		xgifb_info->display2 = XGIFB_DISP_TV;
-	else if (cr32 & XGI_VB_LCD)
-		xgifb_info->display2 = XGIFB_DISP_LCD;
-	else if (cr32 & XGI_VB_CRT2)
-		xgifb_info->display2 = XGIFB_DISP_CRT;
-	else
-		xgifb_info->display2 = XGIFB_DISP_NONE;
+	if (!xgifb_info->display2_force) {
+		if (cr32 & XGI_VB_TV)
+			xgifb_info->display2 = XGIFB_DISP_TV;
+		else if (cr32 & XGI_VB_LCD)
+			xgifb_info->display2 = XGIFB_DISP_LCD;
+		else if (cr32 & XGI_VB_CRT2)
+			xgifb_info->display2 = XGIFB_DISP_CRT;
+		else
+			xgifb_info->display2 = XGIFB_DISP_NONE;
+	}
 
 	if (XGIfb_tvplug != -1)
 		/* PR/TW: Override with option */
@@ -1926,6 +1925,11 @@ static int __devinit xgifb_probe(struct pci_dev *pdev,
 		goto error;
 	}
 
+	if (XGIfb_crt2type != -1) {
+		xgifb_info->display2 = XGIfb_crt2type;
+		xgifb_info->display2_force = true;
+	}
+
 	XGIRegInit(&xgifb_info->dev_info, (unsigned long)hw_info->pjIOAddress);
 
 	xgifb_reg_set(XGISR, IND_XGI_PASSWORD, XGI_PASSWORD);
@@ -2104,6 +2108,8 @@ static int __devinit xgifb_probe(struct pci_dev *pdev,
 
 	if (xgifb_info->hasVB != HASVB_NONE)
 		XGIfb_detect_VB(xgifb_info);
+	else if (xgifb_info->chip != XG21)
+		xgifb_info->display2 = XGIFB_DISP_NONE;
 
 	if (xgifb_info->display2 == XGIFB_DISP_LCD) {
 		if (!enable_dstn) {

drivers/staging/xgifb/XGIfb.h

@@ -86,6 +86,7 @@ struct xgifb_video_info {
 	unsigned int refresh_rate;
 
 	enum xgifb_display_type display2; /* the second display output type */
+	bool display2_force;
 	unsigned char hasVB;
 	unsigned char TV_type;
 	unsigned char TV_plug;

drivers/staging/xgifb/vb_init.c

@@ -1136,7 +1136,13 @@ static void xgifb_read_vbios(struct pci_dev *pdev,
 	}
 	if (vbios_size <= 0x65)
 		goto error;
-	if (!(vbios[0x65] & 0x1)) {
+	/*
+	 * The user can ignore the LVDS bit in the BIOS and force the display
+	 * type.
+	 */
+	if (!(vbios[0x65] & 0x1) &&
+	    (!xgifb_info->display2_force ||
+	     xgifb_info->display2 != XGIFB_DISP_LCD)) {
 		vfree(vbios);
 		return;
 	}