Since vgaarb has been promoted to be a core piece of the pci subsystem
we don't have to open code random guesses anymore, we actually know
this in a platform agnostic way, and there's no need for an x86
specific hack. See also commit
1d38fe6ee6a8 ("PCI/VGA: Move vgaarb to
drivers/pci")
This should not result in any functional change, and the non-x86
multi-gpu pci systems are probably rare enough to not matter (I don't
know of any tbh). But it's a nice cleanup, so let's do it.
There's been a few questions on previous iterations on dri-devel and
irc:
- fb_is_primary_device() seems to be yet another implementation of
this theme, and at least on x86 it checks for both
vga_default_device OR rom shadowing. There shouldn't ever be a case
where rom shadowing gives any additional hints about the boot vga
device, but if there is then the default vga selection in vgaarb
should probably be fixed. And not special-case checks replicated all
over.
- Thomas also brought up that on most !x86 systems
fb_is_primary_device() returns 0, except on sparc/parisc. But these
2 special cases are about platform specific devices and not pci, so
shouldn't have any interactions.
- Furthermore fb_is_primary_device() is a bit a red herring since it's
only used to select the right fbdev driver for fbcon, and not for
the fw handover dance which the aperture helpers handle. At least
for x86 we might want to look into unifying them, but that's a
separate thing.
v2: Extend commit message trying to summarize various discussions.
v4:
- make the test for the primary device easier to read (Javier)
- fix commit message style (i.e., commit 1234 ("..."))
- fix Daniel's S-o-b address
v5:
- add back an S-o-b tag with Daniel's Intel address
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230406132109.32050-3-tzimmermann@suse.de