The vga_is_firmware_default() function is arch-dependent, it's probably
wrong if we simply remove the arch guard. As the VRAM BAR which contains
firmware framebuffer may move, while the lfb_base and lfb_size members of
the screen_info does not change accordingly. In short, it should take the
re-allocation of the PCI BAR into consideration.
With the observation that device drivers or video aperture helpers may
have better knowledge about which PCI bar contains the firmware fb,
which could avoid the need to iterate all of the PCI BARs. But as a PCI
function at pci/vgaarb.c, vga_is_firmware_default() is not suitable to
make such an optimization since it is loaded too early.
There are PCI display controllers that don't have a dedicated VRAM bar,
this function will lose its effectiveness in such a case. Luckily, the
device driver can provide an accurate workaround.
Therefore, this patch introduces a callback that allows the device driver
to tell the VGAARB if the device is the default boot device. Also honor
the comment: "Clients have two callback mechanisms they can use"
Sui Jingfeng (8):
PCI/VGA: Use unsigned type for the io_state variable
PCI/VGA: Deal only with VGA class devices
PCI/VGA: Tidy up the code and comment format
PCI/VGA: Replace full MIT license text with SPDX identifier
video/aperture: Add a helper to detect if an aperture contains
firmware FB
PCI/VGA: Introduce is_boot_device function callback to
vga_client_register
drm/amdgpu: Implement the is_boot_device callback function
drm/radeon: Implement the is_boot_device callback function
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 12 +-
drivers/gpu/drm/drm_aperture.c | 16 +++
drivers/gpu/drm/i915/display/intel_vga.c | 3 +-
drivers/gpu/drm/nouveau/nouveau_vga.c | 2 +-
drivers/gpu/drm/radeon/radeon_device.c | 12 +-
drivers/pci/vgaarb.c | 153 +++++++++++++--------
drivers/vfio/pci/vfio_pci_core.c | 2 +-
drivers/video/aperture.c | 29 ++++
include/drm/drm_aperture.h | 2 +
include/linux/aperture.h | 7 +
include/linux/vgaarb.h | 35 ++---
11 files changed, 184 insertions(+), 89 deletions(-)
--
2.25.1
