linux-kernel - [PATCH 3/3] efi: Add FIRMWARE

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Message-ID: <20251119123011.1187249-8-ardb+git@google.com>
Date: Wed, 19 Nov 2025 13:30:15 +0100
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-efi@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Javier Martinez Canillas <javierm@...hat.com>
Subject: [PATCH 3/3] efi: Add FIRMWARE_EDID support

From: Ard Biesheuvel <ardb@...nel.org>

Add support to non-x86 EFI systems for passing the EDID information
discovered by the EFI stub to the kernel proper.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 drivers/firmware/efi/efi-init.c         | 8 ++++++++
 drivers/firmware/efi/libstub/efi-stub.c | 7 ++++++-
 drivers/firmware/efi/libstub/efistub.h  | 3 ---
 drivers/video/Kconfig                   | 2 +-
 include/linux/efi.h                     | 4 ++++
 5 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efi/efi-init.c b/drivers/firmware/efi/efi-init.c
index 5896f4e699a1..d70bd0ec154f 100644
--- a/drivers/firmware/efi/efi-init.c
+++ b/drivers/firmware/efi/efi-init.c
@@ -64,6 +64,14 @@ struct efi_screen_info efi_screen_info __section(".data");
 
 extern struct screen_info screen_info __alias(efi_screen_info);
 EXPORT_SYMBOL_GPL(screen_info);
+
+#ifdef CONFIG_FIRMWARE_EDID
+const u8 *get_edid_info(void)
+{
+       return efi_screen_info.edid_info.dummy;
+}
+EXPORT_SYMBOL_GPL(get_edid_info);
+#endif
 #endif
 
 static void __init init_screen_info(void)
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
index fe77c285a547..20b606d1cbf0 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -54,8 +54,13 @@ void __weak free_screen_info(struct efi_screen_info *si)
 static struct efi_screen_info *setup_graphics(void)
 {
 	struct efi_screen_info *si, tmp = {};
+	struct edid_info *edid_info = NULL;
 
-	if (efi_setup_graphics(&tmp, NULL) != EFI_SUCCESS)
+#ifdef CONFIG_FIRMWARE_EDID
+	edid_info = &tmp.edid_info;
+#endif
+
+	if (efi_setup_graphics(&tmp.screen_info, edid_info) != EFI_SUCCESS)
 		return NULL;
 
 	si = alloc_screen_info();
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index bdeb28d42a1a..93940592e88e 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -34,9 +34,6 @@
 #define EFI_ALLOC_LIMIT		ULONG_MAX
 #endif
 
-struct edid_info;
-struct screen_info;
-
 extern bool efi_no5lvl;
 extern bool efi_nochunk;
 extern bool efi_nokaslr;
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index d51777df12d1..6526827fbc55 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -63,7 +63,7 @@ endif # HAS_IOMEM
 
 config FIRMWARE_EDID
 	bool "Enable firmware EDID"
-	depends on X86
+	depends on X86 || EFI_GENERIC_STUB
 	help
 	  This enables access to the EDID transferred from the firmware.
 	  On x86, this is from the VESA BIOS. DRM display drivers will
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 75d05dc1b4ee..8d8228d73585 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -28,6 +28,7 @@
 #include <asm/page.h>
 
 #include <linux/screen_info.h>
+#include <video/edid.h>
 
 #define EFI_SUCCESS		0
 #define EFI_LOAD_ERROR		( 1 | (1UL << (BITS_PER_LONG-1)))
@@ -1363,6 +1364,9 @@ void efivars_generic_ops_unregister(void);
 
 struct efi_screen_info {
 	struct screen_info	screen_info;
+#ifdef CONFIG_FIRMWARE_EDID
+	struct edid_info	edid_info;
+#endif
 };
 
 #endif /* _LINUX_EFI_H */
-- 
2.52.0.rc1.455.g30608eb744-goog