firmware/sysfb: Clear screen_info state after consuming it

After consuming the global screen_info_state in sysfb_init(), the
created platform device maintains the firmware framebuffer. Clear
screen_info to avoid conflicting access. Subsequent kexec reboots
now ignore the firmware framebuffer.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>

drivers/firmware/sysfb.c

@@ -71,7 +71,7 @@ EXPORT_SYMBOL_GPL(sysfb_disable);
 
 static __init int sysfb_init(void)
 {
-	struct screen_info *si = &screen_info;
+	const struct screen_info *si = &screen_info;
 	struct simplefb_platform_data mode;
 	const char *name;
 	bool compatible;
@@ -119,6 +119,18 @@ static __init int sysfb_init(void)
 	if (ret)
 		goto err;
 
+	/*
+	 * The firmware framebuffer is now maintained by the created
+	 * device. Disable screen_info after we've consumed it. Prevents
+	 * invalid access during kexec reboots.
+	 *
+	 * TODO: Vgacon still relies on the global screen_info. Make
+	 *       vgacon work with the platform device, so we can clear
+	 *       the screen_info unconditionally.
+	 */
+	if (strcmp(name, "platform-framebuffer"))
+		screen_info.orig_video_isVGA = 0;
+
 	goto unlock_mutex;
 err:
 	platform_device_put(pd);