Re: [PATCH v10 2/4] PCI/VGA: Replace vga_is_firmware_default() with a screen info check

[Mario Limonciello]

On 10/12/25 1:47 PM, Eric Biggers wrote:
> On Sun, Oct 12, 2025 at 01:37:33PM -0500, Mario Limonciello wrote:
> > On 10/12/25 1:23 PM, Eric Biggers wrote:
> > > Hi,
> > >
> > > On Mon, Aug 11, 2025 at 11:26:04AM -0500, Mario Limonciello (AMD) wrote:
> > > > vga_is_firmware_default() checks firmware resources to find the owner
> > > > framebuffer resources to find the firmware PCI device.  This is an
> > > > open coded implementation of screen_info_pci_dev().  Switch to using
> > > > screen_info_pci_dev() instead.
> > > >
> > > > Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > > > Suggested-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > > Signed-off-by: Mario Limonciello (AMD) <superm1@xxxxxxxxxx>
> > >
> > > I'm getting a black screen on boot on mainline, and it bisected to this
> > > commit.  Reverting this commit fixed it.
> > >
> > > Please revert.
> > >
> > > - Eric
> >
> > Can you please share more information about your issue before we jump
> > straight into a revert?  What kind of hardware do you have?  Perhaps a
> > kernel log from mainline and another from mainline with the revert could
> > help identify what's going on?
> >
> > A revert might be the right solution, but I would rather fix the issue if
> > it's plausible to do so.
>
> Relevant hardware is:
>      AMD Ryzen 9 9950X 16-Core Processor
>      Radeon RX 9070
>
> The following message appears in the good log but not the bad log:
>
>      fbcon: amdgpudrmfb (fb0) is primary device
>
> I don't have CONFIG_SCREEN_INFO enabled, so the commit changed
> vga_is_firmware_default() to always return false.

Thanks, that definitely explains it.

> If DRM_AMDGPU depends on SCREEN_INFO now, it needs to select it.
>
> - Eric

Well the question now is which driver should actually select it.

Although it manifested for you in amdgpu, I don't think this is going to 
be an amdgpu unique issue.

Maybe this:

diff --git a/drivers/video/fbdev/core/Kconfig 
b/drivers/video/fbdev/core/Kconfig
index 006638eefa41..ce2544924b0e 100644
--- a/drivers/video/fbdev/core/Kconfig
+++ b/drivers/video/fbdev/core/Kconfig
@@ -5,6 +5,7 @@

 config FB_CORE
        select VIDEO
+       select SCREEN_INFO
        tristate

 config FB_NOTIFY