Re: [REGRESSION] 527139d738d7 ("PCI/sysfs: Convert "rom" to static attribute")

[Bjorn Helgaas <helgaas@kernel.org>]

Hi Ville,

Thanks for the report!

On Fri, Dec 17, 2021 at 12:44:51PM +0200, Ville Syrjälä wrote:
> Hi,
> 
> The pci sysfs "rom" file has disappeared for VGA devices.
> Looks to be a regression from commit 527139d738d7 ("PCI/sysfs:
> Convert "rom" to static attribute").
> 
> Some kind of ordering issue between the sysfs file creation 
> vs. pci_fixup_video() perhaps?

Can you attach your complete "lspci -vv" output?  Also, which is the
default device?  I think there's a "boot_vga" sysfs file that shows
this.  "find /sys -name boot_vga | xargs grep ."

I think the relevant path is something like this:

  acpi_pci_root_add
    pci_acpi_scan_root
      ...
        pci_scan_single_device
          pci_device_add
            device_add
              ...
                sysfs_create_groups
                  ...
                    if (grp->is_visible())
                      pci_dev_rom_attr_is_visible  # after 527139d738d7
                        if (pci_resource_len(pdev, PCI_ROM_RESOURCE))
                          ...
    pci_bus_add_devices
      pci_bus_add_device
        pci_fixup_device(pci_fixup_final)
          pci_fixup_video
            if (vga_default_device() ...)
              # update PCI_ROM_RESOURCE
        pci_create_sysfs_dev_files
          if (pci_resource_len(pdev, PCI_ROM_RESOURCE))
            sysfs_create_bin_file("rom")           # before 527139d738d7

Prior to 527139d738d7, we ran pci_fixup_video() in
pci_bus_add_devices().  The vga_default_device() there might depend on
the fact that we've discovered all the PCI devices.  

After 527139d738d7, we create the "rom" file in pci_device_add(),
which happens as we discover each device, so maybe we don't yet know
which device is the default VGA device.

Bjorn