viafb: introduce strict parameter checking

Refuse to work if wrong parameters are given.  This should improve the
user experience as it will be clear that something is wrong and not
silently ignored.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Scott Fang <ScottFang@viatech.com.cn>
Cc: Joseph Chan <JosephChan@via.com.tw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/via/viafbdev.c

@@ -31,13 +31,13 @@ static char *viafb_name = "Via";
 static u32 pseudo_pal[17];
 
 /* video mode */
-static char *viafb_mode = "640x480";
-static char *viafb_mode1 = "640x480";
+static char *viafb_mode;
+static char *viafb_mode1;
 
 static int viafb_accel = 1;
 
 /* Added for specifying active devices.*/
-char *viafb_active_dev = "";
+char *viafb_active_dev;
 
 /*Added for specify lcd output port*/
 char *viafb_lcd_port = "";
@@ -1327,7 +1327,7 @@ static void retrieve_device_setting(struct viafb_ioctl_setting
 	setting_info->lcd_attributes.lcd_mode = viafb_lcd_mode;
 }
 
-static void parse_active_dev(void)
+static int parse_active_dev(void)
 {
 	viafb_CRT_ON = STATE_OFF;
 	viafb_DVI_ON = STATE_OFF;
@@ -1338,60 +1338,63 @@ static void parse_active_dev(void)
 	   IGA path to devices in SAMM case. */
 	/*    Note: The previous of active_dev is primary device,
 	   and the following is secondary device. */
-	if (!strncmp(viafb_active_dev, "CRT+DVI", 7)) {
+	if (!viafb_active_dev) {
+		viafb_CRT_ON = STATE_ON;
+		viafb_SAMM_ON = STATE_OFF;
+	} else if (!strcmp(viafb_active_dev, "CRT+DVI")) {
 		/* CRT+DVI */
 		viafb_CRT_ON = STATE_ON;
 		viafb_DVI_ON = STATE_ON;
 		viafb_primary_dev = CRT_Device;
-	} else if (!strncmp(viafb_active_dev, "DVI+CRT", 7)) {
+	} else if (!strcmp(viafb_active_dev, "DVI+CRT")) {
 		/* DVI+CRT */
 		viafb_CRT_ON = STATE_ON;
 		viafb_DVI_ON = STATE_ON;
 		viafb_primary_dev = DVI_Device;
-	} else if (!strncmp(viafb_active_dev, "CRT+LCD", 7)) {
+	} else if (!strcmp(viafb_active_dev, "CRT+LCD")) {
 		/* CRT+LCD */
 		viafb_CRT_ON = STATE_ON;
 		viafb_LCD_ON = STATE_ON;
 		viafb_primary_dev = CRT_Device;
-	} else if (!strncmp(viafb_active_dev, "LCD+CRT", 7)) {
+	} else if (!strcmp(viafb_active_dev, "LCD+CRT")) {
 		/* LCD+CRT */
 		viafb_CRT_ON = STATE_ON;
 		viafb_LCD_ON = STATE_ON;
 		viafb_primary_dev = LCD_Device;
-	} else if (!strncmp(viafb_active_dev, "DVI+LCD", 7)) {
+	} else if (!strcmp(viafb_active_dev, "DVI+LCD")) {
 		/* DVI+LCD */
 		viafb_DVI_ON = STATE_ON;
 		viafb_LCD_ON = STATE_ON;
 		viafb_primary_dev = DVI_Device;
-	} else if (!strncmp(viafb_active_dev, "LCD+DVI", 7)) {
+	} else if (!strcmp(viafb_active_dev, "LCD+DVI")) {
 		/* LCD+DVI */
 		viafb_DVI_ON = STATE_ON;
 		viafb_LCD_ON = STATE_ON;
 		viafb_primary_dev = LCD_Device;
-	} else if (!strncmp(viafb_active_dev, "LCD+LCD2", 8)) {
+	} else if (!strcmp(viafb_active_dev, "LCD+LCD2")) {
 		viafb_LCD_ON = STATE_ON;
 		viafb_LCD2_ON = STATE_ON;
 		viafb_primary_dev = LCD_Device;
-	} else if (!strncmp(viafb_active_dev, "LCD2+LCD", 8)) {
+	} else if (!strcmp(viafb_active_dev, "LCD2+LCD")) {
 		viafb_LCD_ON = STATE_ON;
 		viafb_LCD2_ON = STATE_ON;
 		viafb_primary_dev = LCD2_Device;
-	} else if (!strncmp(viafb_active_dev, "CRT", 3)) {
+	} else if (!strcmp(viafb_active_dev, "CRT")) {
 		/* CRT only */
 		viafb_CRT_ON = STATE_ON;
 		viafb_SAMM_ON = STATE_OFF;
-	} else if (!strncmp(viafb_active_dev, "DVI", 3)) {
+	} else if (!strcmp(viafb_active_dev, "DVI")) {
 		/* DVI only */
 		viafb_DVI_ON = STATE_ON;
 		viafb_SAMM_ON = STATE_OFF;
-	} else if (!strncmp(viafb_active_dev, "LCD", 3)) {
+	} else if (!strcmp(viafb_active_dev, "LCD")) {
 		/* LCD only */
 		viafb_LCD_ON = STATE_ON;
 		viafb_SAMM_ON = STATE_OFF;
-	} else {
-		viafb_CRT_ON = STATE_ON;
-		viafb_SAMM_ON = STATE_OFF;
-	}
+	} else
+		return -EINVAL;
+
+	return 0;
 }
 
 static int parse_port(char *opt_str, int *output_interface)
@@ -1820,24 +1823,25 @@ static void viafb_remove_proc(struct proc_dir_entry *viafb_entry)
 	remove_proc_entry("viafb", NULL);
 }
 
-static void parse_mode(const char *str, u32 *xres, u32 *yres)
+static int parse_mode(const char *str, u32 *xres, u32 *yres)
 {
 	char *ptr;
 
+	if (!str) {
+		*xres = 640;
+		*yres = 480;
+		return 0;
+	}
+
 	*xres = simple_strtoul(str, &ptr, 10);
 	if (ptr[0] != 'x')
-		goto out_default;
+		return -EINVAL;
 
 	*yres = simple_strtoul(&ptr[1], &ptr, 10);
 	if (ptr[0])
-		goto out_default;
+		return -EINVAL;
 
-	return;
-
-out_default:
-	printk(KERN_WARNING "viafb received invalid mode string: %s\n", str);
-	*xres = 640;
-	*yres = 480;
+	return 0;
 }
 
 static int __devinit via_pci_probe(struct pci_dev *pdev,
@@ -1874,7 +1878,6 @@ static int __devinit via_pci_probe(struct pci_dev *pdev,
 
 	if (viafb_dual_fb)
 		viafb_SAMM_ON = 1;
-	parse_active_dev();
 	parse_lcd_port();
 	parse_dvi_port();
 
@@ -2192,12 +2195,18 @@ static struct pci_driver viafb_driver = {
 
 static int __init viafb_init(void)
 {
+	u32 dummy;
 #ifndef MODULE
 	char *option = NULL;
 	if (fb_get_options("viafb", &option))
 		return -ENODEV;
 	viafb_setup(option);
 #endif
+	if (parse_mode(viafb_mode, &dummy, &dummy)
+		|| parse_mode(viafb_mode1, &dummy, &dummy)
+		|| parse_active_dev())
+		return -EINVAL;
+
 	printk(KERN_INFO
        "VIA Graphics Intergration Chipset framebuffer %d.%d initializing\n",
 	       VERSION_MAJOR, VERSION_MINOR);