efi/gop: Return EFI_NOT_FOUND if there are no usable GOPs

If we don't find a usable instance of the Graphics Output Protocol
(GOP) because none of them have a framebuffer (i.e. they were all
PIXEL_BLT_ONLY), but all the EFI calls succeeded, we will return
EFI_SUCCESS even though we didn't find a usable GOP.

Fix this by explicitly returning EFI_NOT_FOUND if no usable GOPs are
found, allowing the caller to probe for UGA instead.
Signed-off-by: NArvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: NArd Biesheuvel <ardb@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20191206165542.31469-3-ardb@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

drivers/firmware/efi/libstub/gop.c

@@ -119,7 +119,7 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
 	u64 fb_base;
 	struct efi_pixel_bitmask pixel_info;
 	int pixel_format;
-	efi_status_t status = EFI_NOT_FOUND;
+	efi_status_t status;
 	u32 *handles = (u32 *)(unsigned long)gop_handle;
 	int i;
 
@@ -175,7 +175,7 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
 
 	/* Did we find any GOPs? */
 	if (!first_gop)
-		goto out;
+		return EFI_NOT_FOUND;
 
 	/* EFI framebuffer */
 	si->orig_video_isVGA = VIDEO_TYPE_EFI;
@@ -197,7 +197,7 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
 	si->lfb_size = si->lfb_linelength * si->lfb_height;
 
 	si->capabilities |= VIDEO_CAPABILITY_SKIP_QUIRKS;
-out:
+
 	return status;
 }
 
@@ -237,7 +237,7 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
 	u64 fb_base;
 	struct efi_pixel_bitmask pixel_info;
 	int pixel_format;
-	efi_status_t status = EFI_NOT_FOUND;
+	efi_status_t status;
 	u64 *handles = (u64 *)(unsigned long)gop_handle;
 	int i;
 
@@ -293,7 +293,7 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
 
 	/* Did we find any GOPs? */
 	if (!first_gop)
-		goto out;
+		return EFI_NOT_FOUND;
 
 	/* EFI framebuffer */
 	si->orig_video_isVGA = VIDEO_TYPE_EFI;
@@ -315,7 +315,7 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
 	si->lfb_size = si->lfb_linelength * si->lfb_height;
 
 	si->capabilities |= VIDEO_CAPABILITY_SKIP_QUIRKS;
-out:
+
 	return status;
 }