Revert "fbdev: Prevent probing generic drivers if a FB is already registered"

This reverts commit fb561bf9abde49f7e00fdbf9ed2ccf2d86cac8ee.

With

commit 27599aacbaefcbf2af7b06b0029459bbf682000d
Author: Thomas Zimmermann <[e-mail]>
Date: Tue Jan 25 10:12:18 2022 +0100

fbdev: Hot-unplug firmware fb devices on forced removal

this should be fixed properly and we can remove this somewhat hackish
check here (e.g. this won't catch drm drivers if fbdev emulation isn't
enabled).

Cc: Thomas Zimmermann <[e-mail]>
Cc: Zack Rusin <[e-mail]>
Cc: Javier Martinez Canillas <[e-mail]>
Cc: Zack Rusin <[e-mail]>
Cc: Hans de Goede <[e-mail]>
Cc: Ilya Trukhanov <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Reviewed-by: Javier Martinez Canillas <[e-mail]>
Cc: Peter Jones <[e-mail]>
Cc: [e-mail]
Signed-off-by: Javier Martinez Canillas <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/efifb.c

···
 	char *option = NULL;
 	efi_memory_desc_t md;
 
-	/*
-	 * Generic drivers must not be registered if a framebuffer exists.
-	 * If a native driver was probed, the display hardware was already
-	 * taken and attempting to use the system framebuffer is dangerous.
-	 */
-	if (num_registered_fb > 0) {
-		dev_err(&dev->dev,
-			"efifb: a framebuffer is already registered\n");
-		return -EINVAL;
-	}
-
 	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled)
 		return -ENODEV;
 

drivers/video/fbdev/simplefb.c

···
 	struct simplefb_par *par;
 	struct resource *res, *mem;
 
-	/*
-	 * Generic drivers must not be registered if a framebuffer exists.
-	 * If a native driver was probed, the display hardware was already
-	 * taken and attempting to use the system framebuffer is dangerous.
-	 */
-	if (num_registered_fb > 0) {
-		dev_err(&pdev->dev,
-			"simplefb: a framebuffer is already registered\n");
-		return -EINVAL;
-	}
-
 	if (fb_get_options("simplefb", NULL))
 		return -ENODEV;