Message-ID: <20251124165116.502813-10-tzimmermann@suse.de>
Date: Mon, 24 Nov 2025 17:40:21 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: ardb@...nel.org,
	javierm@...hat.com,
	arnd@...db.de,
	richard.lyu@...e.com
Cc: x86@...nel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linux-riscv@...ts.infradead.org,
	dri-devel@...ts.freedesktop.org,
	linux-hyperv@...r.kernel.org,
	linux-pci@...r.kernel.org,
	linux-fbdev@...r.kernel.org,
	Thomas Zimmermann <tzimmermann@...e.de>
Subject: [PATCH v2 09/10] efi: libstub: Transfer EDID to kernel

Replace struct screen_info with struct sysfb_display_info from the
kernel's sysfb_primary_display and rename functions accordingly.
Transfer the it to the runtime kernel using the kernel's global state
or the config-table entry LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID.

Also rename screen_info.c to primary_display.c and adapt the contained
comment according to the changes.

With CONFIG_FIRMWARE_EDID=y, libstub now transfers the GOP device's
EDID information to the kernel.

Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
---
 drivers/firmware/efi/libstub/Makefile         |  2 +-
 drivers/firmware/efi/libstub/efi-stub-entry.c | 11 ++--
 drivers/firmware/efi/libstub/efi-stub.c       | 41 +++++++++-----
 drivers/firmware/efi/libstub/efistub.h        |  7 ++-
 .../firmware/efi/libstub/primary_display.c    | 56 +++++++++++++++++++
 drivers/firmware/efi/libstub/screen_info.c    | 53 ------------------
 drivers/firmware/efi/libstub/zboot.c          |  4 +-
 7 files changed, 93 insertions(+), 81 deletions(-)
 create mode 100644 drivers/firmware/efi/libstub/primary_display.c
 delete mode 100644 drivers/firmware/efi/libstub/screen_info.c

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 7d15a85d579f..e386ffd009b7 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -80,7 +80,7 @@ $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
 lib-$(CONFIG_EFI_GENERIC_STUB)	+= efi-stub.o string.o intrinsics.o systable.o \
-				   screen_info.o efi-stub-entry.o
+				   primary_display.o efi-stub-entry.o
 
 lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= kaslr.o arm64.o arm64-stub.o smbios.o
diff --git a/drivers/firmware/efi/libstub/efi-stub-entry.c b/drivers/firmware/efi/libstub/efi-stub-entry.c
index 401ecbbdf331..aa85e910fe59 100644
--- a/drivers/firmware/efi/libstub/efi-stub-entry.c
+++ b/drivers/firmware/efi/libstub/efi-stub-entry.c
@@ -14,18 +14,15 @@ static void *kernel_image_addr(void *addr)
 	return addr + kernel_image_offset;
 }
 
-struct screen_info *alloc_screen_info(void)
+struct sysfb_display_info *alloc_primary_display(void)
 {
 	if (IS_ENABLED(CONFIG_ARM))
-		return __alloc_screen_info();
+		return __alloc_primary_display();
 
 	if (IS_ENABLED(CONFIG_X86) ||
 	    IS_ENABLED(CONFIG_EFI_EARLYCON) ||
-	    IS_ENABLED(CONFIG_SYSFB)) {
-		struct sysfb_display_info *dpy = kernel_image_addr(&sysfb_primary_display);
-
-		return &dpy->screen;
-	}
+	    IS_ENABLED(CONFIG_SYSFB))
+		return kernel_image_addr(&sysfb_primary_display);
 
 	return NULL;
 }
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
index 9cb814c5ba1b..42d6073bcd06 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -10,7 +10,7 @@
  */
 
 #include <linux/efi.h>
-#include <linux/screen_info.h>
+#include <linux/sysfb.h>
 #include <asm/efi.h>
 
 #include "efistub.h"
@@ -48,23 +48,33 @@
 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
 static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
 
-void __weak free_screen_info(struct screen_info *si)
-{
-}
+void __weak free_primary_display(struct sysfb_display_info *dpy)
+{ }
 
-static struct screen_info *setup_graphics(void)
+static struct sysfb_display_info *setup_primary_display(void)
 {
-	struct screen_info *si, tmp = {};
+	struct sysfb_display_info *dpy;
+	struct screen_info *screen = NULL;
+	struct edid_info *edid = NULL;
+	efi_status_t status;
 
-	if (efi_setup_graphics(&tmp, NULL) != EFI_SUCCESS)
+	dpy = alloc_primary_display();
+	if (!dpy)
 		return NULL;
+	screen = &dpy->screen;
+#if defined(CONFIG_FIRMWARE_EDID)
+	edid = &dpy->edid;
+#endif
 
-	si = alloc_screen_info();
-	if (!si)
-		return NULL;
+	status = efi_setup_graphics(screen, edid);
+	if (status != EFI_SUCCESS)
+		goto err_free_primary_display;
 
-	*si = tmp;
-	return si;
+	return dpy;
+
+err_free_primary_display:
+	free_primary_display(dpy);
+	return NULL;
 }
 
 static void install_memreserve_table(void)
@@ -145,14 +155,14 @@ efi_status_t efi_stub_common(efi_handle_t handle,
 			     unsigned long image_addr,
 			     char *cmdline_ptr)
 {
-	struct screen_info *si;
+	struct sysfb_display_info *dpy;
 	efi_status_t status;
 
 	status = check_platform_features();
 	if (status != EFI_SUCCESS)
 		return status;
 
-	si = setup_graphics();
+	dpy = setup_primary_display();
 
 	efi_retrieve_eventlog();
 
@@ -172,7 +182,8 @@ efi_status_t efi_stub_common(efi_handle_t handle,
 
 	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
 
-	free_screen_info(si);
+	free_primary_display(dpy);
+
 	return status;
 }
 
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index b2fb0c3fa721..979a21818cc1 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -36,6 +36,7 @@
 
 struct edid_info;
 struct screen_info;
+struct sysfb_display_info;
 
 extern bool efi_no5lvl;
 extern bool efi_nochunk;
@@ -1175,9 +1176,9 @@ efi_enable_reset_attack_mitigation(void) { }
 
 void efi_retrieve_eventlog(void);
 
-struct screen_info *alloc_screen_info(void);
-struct screen_info *__alloc_screen_info(void);
-void free_screen_info(struct screen_info *si);
+struct sysfb_display_info *alloc_primary_display(void);
+struct sysfb_display_info *__alloc_primary_display(void);
+void free_primary_display(struct sysfb_display_info *dpy);
 
 void efi_cache_sync_image(unsigned long image_base,
 			  unsigned long alloc_size);
diff --git a/drivers/firmware/efi/libstub/primary_display.c b/drivers/firmware/efi/libstub/primary_display.c
new file mode 100644
index 000000000000..cdaebab26514
--- /dev/null
+++ b/drivers/firmware/efi/libstub/primary_display.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/efi.h>
+#include <linux/sysfb.h>
+
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+/*
+ * There are two ways of populating the core kernel's sysfb_primary_display
+ * via the stub:
+ *
+ *   - using a configuration table, which relies on the EFI init code to
+ *     locate the table and copy the contents; or
+ *
+ *   - by linking directly to the core kernel's copy of the global symbol.
+ *
+ * The latter is preferred because it makes the EFIFB earlycon available very
+ * early, but it only works if the EFI stub is part of the core kernel image
+ * itself. The zboot decompressor can only use the configuration table
+ * approach.
+ */
+
+static efi_guid_t primary_display_guid = LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID;
+
+struct sysfb_display_info *__alloc_primary_display(void)
+{
+	struct sysfb_display_info *dpy;
+	efi_status_t status;
+
+	status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
+			     sizeof(*dpy), (void **)&dpy);
+
+	if (status != EFI_SUCCESS)
+		return NULL;
+
+	memset(dpy, 0, sizeof(*dpy));
+
+	status = efi_bs_call(install_configuration_table,
+			     &primary_display_guid, dpy);
+	if (status == EFI_SUCCESS)
+		return dpy;
+
+	efi_bs_call(free_pool, dpy);
+	return NULL;
+}
+
+void free_primary_display(struct sysfb_display_info *dpy)
+{
+	if (!dpy)
+		return;
+
+	efi_bs_call(install_configuration_table, &primary_display_guid, NULL);
+	efi_bs_call(free_pool, dpy);
+}
diff --git a/drivers/firmware/efi/libstub/screen_info.c b/drivers/firmware/efi/libstub/screen_info.c
deleted file mode 100644
index 5d3a1e32d177..000000000000
--- a/drivers/firmware/efi/libstub/screen_info.c
+++ /dev/null
@@ -1,53 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-#include <linux/efi.h>
-#include <linux/screen_info.h>
-
-#include <asm/efi.h>
-
-#include "efistub.h"
-
-/*
- * There are two ways of populating the core kernel's struct screen_info via the stub:
- * - using a configuration table, like below, which relies on the EFI init code
- *   to locate the table and copy the contents;
- * - by linking directly to the core kernel's copy of the global symbol.
- *
- * The latter is preferred because it makes the EFIFB earlycon available very
- * early, but it only works if the EFI stub is part of the core kernel image
- * itself. The zboot decompressor can only use the configuration table
- * approach.
- */
-
-static efi_guid_t screen_info_guid = LINUX_EFI_SCREEN_INFO_TABLE_GUID;
-
-struct screen_info *__alloc_screen_info(void)
-{
-	struct screen_info *si;
-	efi_status_t status;
-
-	status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
-			     sizeof(*si), (void **)&si);
-
-	if (status != EFI_SUCCESS)
-		return NULL;
-
-	memset(si, 0, sizeof(*si));
-
-	status = efi_bs_call(install_configuration_table,
-			     &screen_info_guid, si);
-	if (status == EFI_SUCCESS)
-		return si;
-
-	efi_bs_call(free_pool, si);
-	return NULL;
-}
-
-void free_screen_info(struct screen_info *si)
-{
-	if (!si)
-		return;
-
-	efi_bs_call(install_configuration_table, &screen_info_guid, NULL);
-	efi_bs_call(free_pool, si);
-}
diff --git a/drivers/firmware/efi/libstub/zboot.c b/drivers/firmware/efi/libstub/zboot.c
index c47ace06f010..4b76f74c56da 100644
--- a/drivers/firmware/efi/libstub/zboot.c
+++ b/drivers/firmware/efi/libstub/zboot.c
@@ -26,9 +26,9 @@ void __weak efi_cache_sync_image(unsigned long image_base,
 	// executable code loaded into memory to be safe for execution.
 }
 
-struct screen_info *alloc_screen_info(void)
+struct sysfb_display_info *alloc_primary_display(void)
 {
-	return __alloc_screen_info();
+	return __alloc_primary_display();
 }
 
 asmlinkage efi_status_t __efiapi
-- 
2.51.1

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