[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20250722153322.GA2785882@bhelgaas>
Date: Tue, 22 Jul 2025 10:33:22 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Mario Limonciello <superm1@...nel.org>
Cc: David Airlie <airlied@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
Alex Deucher <alexander.deucher@....com>,
Christian König <christian.koenig@....com>,
Simona Vetter <simona@...ll.ch>, Lukas Wunner <lukas@...ner.de>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Woodhouse <dwmw2@...radead.org>,
Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
Alex Williamson <alex.williamson@...hat.com>,
Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
"open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
open list <linux-kernel@...r.kernel.org>,
"open list:INTEL IOMMU (VT-d)" <iommu@...ts.linux.dev>,
"open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
"open list:VFIO DRIVER" <kvm@...r.kernel.org>,
"open list:SOUND" <linux-sound@...r.kernel.org>,
Daniel Dadap <ddadap@...dia.com>,
Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v9 8/9] fbcon: Use screen info to find primary device
On Tue, Jul 22, 2025 at 09:45:28AM -0500, Mario Limonciello wrote:
> On 7/22/25 9:38 AM, Bjorn Helgaas wrote:
> > On Thu, Jul 17, 2025 at 12:38:11PM -0500, Mario Limonciello wrote:
> > > From: Mario Limonciello <mario.limonciello@....com>
> > >
> > > 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.
> >
> > This relies on screen_info, which I think is an x86 BIOS-ism. Isn't
> > there a UEFI console path? How does that compare with this? Is that
> > relevant or is it something completely different?
>
> When I created and tested this I actually did this on a UEFI system (which
> provides a UEFI GOP driver).
I guess screen_info is actually *not* an x86 BIOS-ism, and on UEFI
systems, we do actually rely on UEFI, e.g., in efi_setup_gop(),
alloc_screen_info(), init_screen_info()?
But this patch is x86-specific, so I'm guessing the same problem could
occur on arm64, Loongson, or other UEFI platforms, and this series
doesn't address those?
> > > bool video_is_primary_device(struct device *dev)
> > > {
> > > +#ifdef CONFIG_SCREEN_INFO
> > > + struct screen_info *si = &screen_info;
> > > +#endif
> > > struct pci_dev *pdev;
> > > if (!dev_is_pci(dev))
> > > @@ -34,7 +38,18 @@ 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;
> > > +
> > > +#ifdef CONFIG_SCREEN_INFO
> > > + if (pdev == screen_info_pci_dev(si))
> > > + return true;
> > > +#endif
> > > +
> > > + return false;
> > > }
> > > EXPORT_SYMBOL(video_is_primary_device);
> > > --
> > > 2.43.0
> > >
>
Powered by blists - more mailing lists