[-next 0/5] Add the pci_is_vga() helper and use it

[Sui Jingfeng <sui.jingfeng@linux.dev>]

From: Sui Jingfeng <suijingfeng@loongson.cn>

The PCI code and ID assignment specification defined four types of
display controllers for the display base class(03h), and the devices
with 0x00h sub-class code are VGA devices. VGA devices with programming
interface 0x00 is VGA-compatible, VGA devices with programming interface
0x01 are 8514-compatible controllers. Besides, PCI_CLASS_NOT_DEFINED_VGA
is defined to provide backward compatibility for devices that were built
before the class code field was defined. Thus, PCI(e) device with the
PCI_CLASS_NOT_DEFINED_VGA class code should also be handled as the normal
VGA-compatible devices.

Compared with the "if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)" code,
the newly implemented pci_is_vga() is shorter and straightforward. So it
is more easy to use. It is designed as a inline function, the more common
case "if ((pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA))" is put before the
less common case "if ((pdev->class >> 8) == PCI_CLASS_NOT_DEFINED_VGA)",
so there should no performance penalty.

Sui Jingfeng (5):
  PCI: Add the pci_is_vga() helper
  PCI/VGA: Deal with VGA devices
  PCI/sysfs: Use pci_is_vga() helper
  drm/virgpu: Switch to pci_is_vga()
  drm/qxl: Switch to pci_is_vga()

 drivers/gpu/drm/qxl/qxl_drv.c        | 11 +++--------
 drivers/gpu/drm/virtio/virtgpu_drv.c |  2 +-
 drivers/pci/pci-sysfs.c              |  6 +++---
 drivers/pci/vgaarb.c                 | 19 +++++++++----------
 include/linux/pci.h                  | 27 +++++++++++++++++++++++++++
 5 files changed, 43 insertions(+), 22 deletions(-)


base-commit: 43cc31da9146f9ce60e4a03d96ef0807c2cdac94
-- 
2.34.1