Currently, the default VGA device selection is not perfect. Potential
problems are:
1) This function is a no-op on non-x86 architectures.
2) It does not take the PCI Bar may get relocated into consideration.
3) It is not effective for the PCI device without a dedicated VRAM Bar.
4) It is device-agnostic, thus it has to waste the effort to iterate all
of the PCI Bar to find the VRAM aperture.
5) It has invented lots of methods to determine which one is the default
boot device on a multiple video card coexistence system. But this is
still a policy because it doesn't give the user a choice to override.
With the observation that device drivers or video aperture helpers may
have better knowledge about which PCI bar contains the firmware FB,
This patch tries to solve the above problems by introducing a function
callback to the vga_client_register() function interface. DRM device
drivers for the PCI device need to register the is_boot_device() function
callback during the driver loading time. Once the driver binds the device
successfully, VRAARB will call back to the driver. This gives the device
drivers a chance to provide accurate boot device identification. Which in
turn unlock the abitration service to non-x86 architectures. A device
driver can also pass a NULL pointer to the keep the original behavior.
Sui Jingfeng (4):
video/aperture: Add a helper to detect if an aperture contains
firmware FB
PCI/VGA: Improve the default VGA device selection
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 | 21 +++++++++++++++-
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 | 8 +++---
11 files changed, 104 insertions(+), 10 deletions(-)
--
2.25.1
