aux/vga: fix switching with different mode

Prior to switching display, switch to text mode 3, which
is supported by anything, then set display, search for the
desired mode, load it if found. If not found, set the display
to the old one and switch to the old mode back.

sys/src/cmd/aux/vga/vesa.c

@@ -28,7 +28,7 @@ struct Vbe
 	uchar	*modebuf;
 	int	dspcon;	/* connected displays bitmask */
 	int	dspact;	/* active displays bitmask */
-	void (*scale)(Vga*, Ctlr*, int);
+	void (*scale)(Vga*, Ctlr*);
 };
 
 struct Vmode
@@ -100,7 +100,7 @@ int vbecheck(Vbe*);
 uchar *vbemodes(Vbe*);
 int vbemodeinfo(Vbe*, int, Vmode*);
 int vbegetmode(Vbe*);
-int vbesetmode(Vbe*, int, int);
+int vbesetmode(Vbe*, int);
 void vbeprintinfo(Vbe*);
 void vbeprintmodeinfo(Vbe*, int, char*);
 int vbesnarf(Vbe*, Vga*);
@@ -111,6 +111,7 @@ void fixbios(Vbe*);
 uchar* vbesetup(Vbe*, Ureg*, int);
 int vbecall(Vbe*, Ureg*);
 int setdisplay(Vbe *vbe, int display);
+int getdisplay(Vbe *vbe);
 
 int
 dbvesa(Vga* vga)
@@ -142,32 +143,41 @@ dbvesa(Vga* vga)
 Mode*
 dbvesamode(char *size)
 {
-	int i, width, nargs;
+	int i, width, nargs, display;
+	int oldmode, olddisplay;
 	uchar *p, *ep;
 	Attr *a;
 	Vmode vm;
 	Mode *m;
 	Modelist *l;
-	char *args[4], *scale, *display;
+	char *args[4], *scale;
 
 	if(vbe == nil)
 		return nil;
 
 	scale = nil;
-	display = nil;
+	display = 0;
+	oldmode = olddisplay = 0;
 	nargs = getfields(size, args, 4, 0, ",");
 	if(nargs > 1){
 		if(args[1][0] == '#'){
-			display = &args[1][1];
+			display = atoi(&args[1][1]);
 			if(nargs > 2)
 				scale = args[2];
 		}else if(args[1][0] == 's'){
 			scale = args[1];
 			if(nargs > 2)
-				display = &args[2][1];
+				display = atoi(&args[2][1]);
 		}
 	}
 
+	if(display != 0){
+		olddisplay = getdisplay(vbe);
+		oldmode = vbegetmode(vbe);
+		if(setdisplay(vbe, display) < 0)
+			return nil;
+	}
+
 	if(strncmp(size, "0x", 2) == 0){
 		if(vbemodeinfo(vbe, strtol(size+2, nil, 16), &vm) == 0)
 			goto havemode;
@@ -190,10 +200,17 @@ dbvesamode(char *size)
 			}
 		}
 	}
+
+	if(display != 0 && setdisplay(vbe, olddisplay) == 0)
+		vbesetmode(vbe, oldmode);
+
 	werrstr("no such vesa mode");
 	return nil;
 
 havemode:
+	if(display != 0 && setdisplay(vbe, olddisplay) == 0)
+		vbesetmode(vbe, oldmode);
+
 	m = alloc(sizeof(Mode));
 	m->x = vm.dx;
 	m->y = vm.dy;
@@ -248,11 +265,11 @@ havemode:
 	}
 
 	/* display id */
-	if(display != nil){
+	if(display != 0){
 		a = alloc(sizeof(Attr));
 		a->attr = "display";
 		a->val = alloc(2);
-		strncpy(a->val, display, 2);
+		a->val[0] = '0' + display;
 
 		a->next = m->attr;
 		m->attr = a;
@@ -302,6 +319,7 @@ static void
 load(Vga* vga, Ctlr* ctlr)
 {
 	int mode, display;
+	int oldmode, olddisplay;
 	char *ds;
 
 	if(vbe == nil)
@@ -309,16 +327,29 @@ load(Vga* vga, Ctlr* ctlr)
 	mode = atoi(dbattr(vga->mode->attr, "id"));
 	ds = dbattr(vga->mode->attr, "display");
 	display = ds == nil ? 0 : atoi(ds);
+	olddisplay = oldmode = 0;
 
 	/* need to reset scaling before switching displays */
 	if(vbe->scale != nil)
-		vbe->scale(vga, ctlr, 1);
+		vbe->scale(nil, nil);
 
-	if(vbesetmode(vbe, mode, display) < 0){
+	if(display != 0){
+		olddisplay = getdisplay(vbe);
+		oldmode = vbegetmode(vbe);
+	}
+
+	if(setdisplay(vbe, display) < 0){
+		ctlr->flag |= Ferror;
+		fprint(2, "vbesetmode: %r\n");
+	}else if(vbesetmode(vbe, mode) < 0){
+		if(display != 0){
+			setdisplay(vbe, olddisplay);
+			vbesetmode(vbe, oldmode);
+		}
 		ctlr->flag |= Ferror;
 		fprint(2, "vbesetmode: %r\n");
 	}else if(vbe->scale != nil)
-		vbe->scale(vga, ctlr, 0);
+		vbe->scale(vga, ctlr);
 }
 
 static void
@@ -351,7 +382,7 @@ dump(Vga*, Ctlr*)
 }
 
 static void
-intelscale(Vga* vga, Ctlr* ctlr, int reset)
+intelscale(Vga* vga, Ctlr* ctlr)
 {
 	Ureg u;
 	int cx;
@@ -360,31 +391,31 @@ intelscale(Vga* vga, Ctlr* ctlr, int reset)
 	if(vbe == nil)
 		error("no vesa bios\n");
 
-	/* NOTE: intel doesn't support "aspect" scaling mode :( */
+	if(vga == nil)
-	scale = dbattr(vga->mode->attr, "scale");
-	if(scale == nil)
-		cx = 0;
-	else if(strcmp(scale, "scalefull") == 0)
 		cx = 4;
 	else{
-		ctlr->flag |= Ferror;
+		/* NOTE: intel doesn't support "aspect" scaling mode :( */
-		fprint(2, "vbescale: unsupported mode %s\n", scale);
+		scale = dbattr(vga->mode->attr, "scale");
-		return;
+		if(scale == nil)
+			cx = 0;
+		else if(strcmp(scale, "scalefull") == 0)
+			cx = 4;
+		else{
+			ctlr->flag |= Ferror;
+			fprint(2, "vbescale: unsupported mode %s\n", scale);
+			return;
+		}
 	}
-	if(reset)
-		cx = 4;
 
 	vbesetup(vbe, &u, 0x5F61);
 	u.bx = 0;
 	u.cx = cx; /* horizontal */
 	u.dx = cx; /* vertical */
 	vbecall(vbe, &u);
-	if(u.ax != 0x5f)
-		fprint(2, "vbescale: %#.4lux", u.ax);
 }
 
 static void
-nvidiascale(Vga* vga, Ctlr* ctlr, int reset)
+nvidiascale(Vga* vga, Ctlr* ctlr)
 {
 	Ureg u;
 	int cx;
@@ -393,26 +424,26 @@ nvidiascale(Vga* vga, Ctlr* ctlr, int reset)
 	if(vbe == nil)
 		error("no vesa bios\n");
 
-	scale = dbattr(vga->mode->attr, "scale");
+	if(vga == nil)
-	if(scale == nil)
-		cx = 1;
-	else if(strcmp(scale, "scaleaspect") == 0)
-		cx = 3;
-	else if(strcmp(scale, "scalefull") == 0)
 		cx = 0;
 	else{
-		ctlr->flag |= Ferror;
+		scale = dbattr(vga->mode->attr, "scale");
-		fprint(2, "vbescale: unsupported mode %s\n", scale);
+		if(scale == nil)
-		return;
+			cx = 1;
+		else if(strcmp(scale, "scaleaspect") == 0)
+			cx = 3;
+		else if(strcmp(scale, "scalefull") == 0)
+			cx = 0;
+		else{
+			ctlr->flag |= Ferror;
+			fprint(2, "vbescale: unsupported mode %s\n", scale);
+			return;
+		}
 	}
-	if(reset)
-		cx = 0;
 
 	vbesetup(vbe, &u, 0x4F14);
 	u.bx = 0x102;
 	u.cx = cx;
-	if(vbecall(vbe, &u) < 0)
-		fprint(2, "vbescale: %r\n");
 }
 
 Ctlr vesa = {
@@ -864,20 +895,25 @@ int
 vbegetmode(Vbe *vbe)
 {
 	Ureg u;
+	char size[32];
+	Mode *m;
 
-	vbesetup(vbe, &u, 0x4F03);
+	vbesetup(vbe, &u, 0x5F29);
-	if(vbecall(vbe, &u) < 0)
+	u.bx = 0x8000; /* current mode */
-		return 0;
+	vbecall(vbe, &u);
-	return u.bx;
+	if(u.ax != 0x5f)
+		return -1;
+	snprint(size, sizeof(size), "%dx%dx%d",
+		(int)u.bx>>16, (int)u.bx & 0xffff, (int)u.cx & 0xff);
+	m = dbvesamode(size);
+	return m == nil ? -1 : atoi(dbattr(m->attr, "id"));
 }
 
 int
-vbesetmode(Vbe *vbe, int id, int display)
+vbesetmode(Vbe *vbe, int id)
 {
 	Ureg u;
 
-	if(setdisplay(vbe, display) < 0)
-		return -1;
 	vbesetup(vbe, &u, 0x4F02);
 	u.bx = id;
 	if(id != 3)
@@ -895,7 +931,7 @@ vesatextmode(void)
 	}
 	if(vbecheck(vbe) < 0)
 		error("vbecheck: %r\n");
-	if(vbesetmode(vbe, 3, 0) < 0)
+	if(vbesetmode(vbe, 3) < 0)
 		error("vbesetmode: %r\n");
 }
 
@@ -928,6 +964,23 @@ vbeddcedid(Vbe *vbe, Edid *e)
 	return 0;
 }
 
+int
+getdisplay(Vbe *vbe)
+{
+	int i;
+
+	for(i = 0; i < 8; i++)
+		if(vbe->dspact & 1<<i)
+			return i+1;
+
+	/* fallback to a connected one */
+	for(i = 0; i < 8; i++)
+		if(vbe->dspcon & 1<<i)
+			return i+1;
+
+	return 0;
+}
+
 int
 setdisplay(Vbe *vbe, int display)
 {
@@ -937,6 +990,9 @@ setdisplay(Vbe *vbe, int display)
 	if(display == 0)
 		return 0;
 
+	/* switch to common mode before trying */
+	vbesetmode(vbe, 3);
+
 	cx = 1<<(display-1);
 	if(vbe->dspcon & cx){
 		vbesetup(vbe, &u, 0x5F64);