On Mon, Aug 11, 2025 at 11:26:05AM -0500, Mario Limonciello (AMD) wrote: > On systems with non VGA GPUs fbcon can't find the primary GPU because > video_is_primary_device() only checks the VGA arbiter. > > Add a screen info check to video_is_primary_device() so that callers > can get accurate data on such systems.
I have a question regarding this change. To me, the function name video_is_primary_device() implies that there is only one primary GPU. I would also expect that the 'boot_display' attribute added later in the patch series based on this function is only set for one GPU, but that is not necessarily the case. Since I'm working on a user-space program that reads the 'boot_display' attribute, I need to know what behavior is intended in order to do a correct implementation. > > Reviewed-by: Thomas Zimmermann <[email protected]> > Suggested-by: Thomas Zimmermann <[email protected]> > Suggested-by: Bjorn Helgaas <[email protected]> > Signed-off-by: Mario Limonciello (AMD) <[email protected]> > --- > v10: > * Rebase on 6.17-rc1 > * Squash 'fbcon: Stop using screen_info_pci_dev()' > --- > arch/x86/video/video-common.c | 25 ++++++++++++++++++++++++- > 1 file changed, 24 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c > index 81fc97a2a837a..e0aeee99bc99e 100644 > --- a/arch/x86/video/video-common.c > +++ b/arch/x86/video/video-common.c > @@ -9,6 +9,7 @@ > > #include <linux/module.h> > #include <linux/pci.h> > +#include <linux/screen_info.h> > #include <linux/vgaarb.h> > > #include <asm/video.h> > @@ -27,6 +28,11 @@ EXPORT_SYMBOL(pgprot_framebuffer); > > bool video_is_primary_device(struct device *dev) > { > +#ifdef CONFIG_SCREEN_INFO > + struct screen_info *si = &screen_info; > + struct resource res[SCREEN_INFO_MAX_RESOURCES]; > + ssize_t i, numres; > +#endif > struct pci_dev *pdev; > > if (!dev_is_pci(dev)) > @@ -34,7 +40,24 @@ bool video_is_primary_device(struct device *dev) > > pdev = to_pci_dev(dev); > > - return (pdev == vga_default_device()); > + if (!pci_is_display(pdev)) > + return false; > + > + if (pdev == vga_default_device()) > + return true; This can mark a VGA device as primary GPU. > + > +#ifdef CONFIG_SCREEN_INFO > + numres = screen_info_resources(si, res, ARRAY_SIZE(res)); > + for (i = 0; i < numres; ++i) { > + if (!(res[i].flags & IORESOURCE_MEM)) > + continue; > + > + if (pci_find_resource(pdev, &res[i])) > + return true; > + } > +#endif And then the new code can also choose a primary GPU. > + > + return false; > } > EXPORT_SYMBOL(video_is_primary_device); > In particular, I have hardware that has this exact configuration where two GPUs are marked as primary and have a 'boot_display' attribute: the first one through vga_default_device(), the second one through the new detection method. Is this intended? Kind regards Aaron
