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    SubjectRe: Ignore disabled ROM resources at setup
    On 8/30/05, Linus Torvalds <torvalds@osdl.org> wrote:
    >
    >
    > On Mon, 29 Aug 2005, David S. Miller wrote:
    > >
    > > So I think the kernel, by not enabling the ROM, is doing the
    > > right thing here.
    >
    > Notice that on ppc even older versions didn't actually _enable_ the rom,
    > but they would write the non-enabled address to the PCI_ROM_ADDRESS
    > register, so that anybody who read that register would see _where_ the ROM
    > would be enabled if it was enabled.
    >
    > That's the thing that changed in the commit Ben dislikes. Now, if the ROM
    > is disabled, we won't even write the disabled address to the PCI register,
    > because it led to trouble on some strange Matrox card. Probably a card
    > that nobody has ever used on PPC, and certainly not on a Powerbook, so in
    > that sense the apparent breakage on ppc is arguably "unnecessary" as far
    > as Ben is concerned.
    >
    > But I notice the problem: pci_enable_rom() is indeed broken with the
    > change.
    >
    > Ben, does this (totally untested) patch fix it for you?
    >
    > Linus
    >
    > ----
    > diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c
    > --- a/drivers/pci/rom.c
    > +++ b/drivers/pci/rom.c
    > @@ -23,11 +23,14 @@
    > */
    > static void pci_enable_rom(struct pci_dev *pdev)
    > {
    > - u32 rom_addr;
    > + struct resource *res = pdev->resource + PCI_ROM_RESOURCE;
    > + struct pci_bus_region region;
    >
    > - pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
    > - rom_addr |= PCI_ROM_ADDRESS_ENABLE;
    > - pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
    > + if (!res->flags)
    > + return;
    > +
    > + pcibios_resource_to_bus(pdev, &region, res);
    > + pci_write_config_dword(pdev, pdev->rom_base_reg, region.start | PCI_ROM_ADDRESS_ENABLE);
    > }

    I was reading the status out of the PCI config space to account for
    our friend X which enables ROMs without informing the OS. With X
    around PCI config space can get out of sync with the kernel
    structures.


    >
    > /**
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    --
    Jon Smirl
    jonsmirl@gmail.com
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