PCI/VGA: Select SCREEN_INFO on X86

commit 337bf13 ("PCI/VGA: Replace vga_is_firmware_default() with a
screen info check") introduced an implicit dependency upon SCREEN_INFO by
removing the open coded implementation.

If a user didn't have CONFIG_SCREEN_INFO set, vga_is_firmware_default()
would now return false.  SCREEN_INFO is only used on X86 so add a
conditional select for SCREEN_INFO to ensure that the VGA arbiter works as
intended.

Fixes: 337bf13 ("PCI/VGA: Replace vga_is_firmware_default() with a screen info check")
Reported-by: Eric Biggers <[email protected]>
Closes: https://lore.kernel.org/linux-pci/20251012182302.GA3412@sol/
Suggested-by: Thomas Zimmermann <[email protected]>
Signed-off-by: Mario Limonciello (AMD) <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Thomas Zimmermann <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Tested-by: Eric Biggers <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: superm1

drivers/pci/Kconfig

@@ -306,6 +306,7 @@ config VGA_ARB
 	bool "VGA Arbitration" if EXPERT
 	default y
 	depends on (PCI && !S390)
+	select SCREEN_INFO if X86
 	help
 	  Some "legacy" VGA devices implemented on PCI typically have the same
 	  hard-decoded addresses as they did on ISA. When multiple PCI devices

drivers/pci/vgaarb.c

@@ -556,10 +556,8 @@ EXPORT_SYMBOL(vga_put);
 
 static bool vga_is_firmware_default(struct pci_dev *pdev)
 {
-#ifdef CONFIG_SCREEN_INFO
-	struct screen_info *si = &screen_info;
-
-	return pdev == screen_info_pci_dev(si);
+#if defined CONFIG_X86
+	return pdev == screen_info_pci_dev(&screen_info);
 #else
 	return false;
 #endif