On Wed, Mar 22, 2017 at 03:30:29PM +0000, Ard Biesheuvel wrote:

On UEFI systems, the PCI subsystem is enumerated by the firmware,
and if a graphical framebuffer is exposed by a PCI device, its base
address and size are exposed to the OS via the Graphics Output
Protocol (GOP).

On arm64 PCI systems, the entire PCI hierarchy is reconfigured from
scratch at boot. This may result in the GOP framebuffer address to
become stale, if the BAR covering the framebuffer is modified. This
will cause the framebuffer to become unresponsive, and may in some
cases result in unpredictable behavior if the range is reassigned to
another device.

Hm, commit message seems to indicate the issue is restricted to arm64,
yet there's no IS_ENABLED(ARM64) to constrain the added code to that arch?

+DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, efifb_fixup_resources);

Maybe this can be constrained to PCI_BASE_CLASS_DISPLAY?

Thanks,

Lukas