Re: [PATCH v2] PCI/VGA: Select SCREEN_INFO

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Oct 13, 2025 at 12:55:25PM -0500, Bjorn Helgaas wrote:
> On Mon, Oct 13, 2025 at 10:44:23AM -0500, Mario Limonciello (AMD) wrote:
> > commit 337bf13aa9dda ("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.  Add a select for SCREEN_INFO to ensure that the
> > VGA arbiter works as intended. Also drop the now dead code.
> > 
> > Reported-by: Eric Biggers <ebiggers@kernel.org>
> > Closes: https://lore.kernel.org/linux-pci/20251012182302.GA3412@sol/
> > Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
> > Fixes: 337bf13aa9dda ("PCI/VGA: Replace vga_is_firmware_default() with a screen info check")
> > Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> 
> Applied to for-linus for v6.18, thanks!

Oops, dropped because of this regression:

  https://lore.kernel.org/r/176038554347.1442.9483731885505420131@15dd6324cc71

> > ---
> > v2:
> >  * drop dead code (Ilpo)
> > ---
> >  drivers/pci/Kconfig  | 1 +
> >  drivers/pci/vgaarb.c | 8 +-------
> >  2 files changed, 2 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> > index 7065a8e5f9b14..c35fed47addd5 100644
> > --- a/drivers/pci/Kconfig
> > +++ b/drivers/pci/Kconfig
> > @@ -306,6 +306,7 @@ config VGA_ARB
> >  	bool "VGA Arbitration" if EXPERT
> >  	default y
> >  	depends on (PCI && !S390)
> > +	select SCREEN_INFO
> >  	help
> >  	  Some "legacy" VGA devices implemented on PCI typically have the same
> >  	  hard-decoded addresses as they did on ISA. When multiple PCI devices
> > diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> > index b58f94ee48916..8c8c420ff5b55 100644
> > --- a/drivers/pci/vgaarb.c
> > +++ b/drivers/pci/vgaarb.c
> > @@ -556,13 +556,7 @@ 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);
> > -#else
> > -	return false;
> > -#endif
> > +	return pdev == screen_info_pci_dev(&screen_info);
> >  }
> >  
> >  static bool vga_arb_integrated_gpu(struct device *dev)
> > -- 
> > 2.43.0
> >