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    SubjectRe: [PATCH] add legacy resources to sysfs
    On Tue, Dec 21, 2004 at 12:47:44PM -0800, Jesse Barnes wrote:
    > + * Find the base of legacy memory for @dev. This is typically the first
    > + * megabyte of bus address space for @dev or is simply 0 on platforms whose
    > + * chipsets support legacy I/O and memory routing. Returns 0 on success
    > + * or a standard error code on failure.
    > +int ia64_pci_get_legacy_mem(struct pci_bus *bus, unsigned long *addr)
    > +{
    > + *addr = 0;
    > + return 0;
    > +}

    This is a slightly klunky interface. How about:

    * Find the base of legacy memory for @dev. This is typically the first
    * megabyte of bus address space for @dev or is simply 0 on platforms whose
    * chipsets support legacy I/O and memory routing. Returns the base address
    * or an error pointer if an error occurred

    The generic one is too trivial to demonstrate with, but the sn2 one
    makes more sense:

    > ===== arch/ia64/sn/pci/pci_dma.c 1.2 vs edited =====
    > +int sn_pci_get_legacy_mem(struct pci_bus *bus, unsigned long *addr)
    > +{
    > + if (!SN_PCIBUS_BUSSOFT(bus))
    > + return -ENODEV;
    > +
    > + *addr = SN_PCIBUS_BUSSOFT(bus)->bs_legacy_mem | __IA64_UNCACHED_OFFSET;
    > +
    > + return 0;
    > +}

    int sn_pci_get_legacy_mem(struct pci_bus *bus)
    {
    if (!SN_PCIBUS_BUSSOFT(bus))
    return ERR_PTR(-ENODEV);
    return SN_PCIBUS_BUSSOFT(bus)->bs_legacy_mem | __IA64_UNCACHED_OFFSET;
    }

    > b->class_dev.class = &pcibus_class;
    > sprintf(b->class_dev.class_id, "%04x:%02x", pci_domain_nr(b), bus);
    > error = class_device_register(&b->class_dev);
    > +
    > if (error)
    > goto class_dev_reg_err;

    Actually, I rather dislike having the newline there. It implies a logical
    separation between registering and testing for the error, whereas the logical
    separation is much more like this:

    b->class_dev.class = &pcibus_class;
    sprintf(b->class_dev.class_id, "%04x:%02x", pci_domain_nr(b), bus);
    error = class_device_register(&b->class_dev);
    if (error)
    goto class_dev_reg_err;

    error = class_device_create_file(...)

    --
    "Next the statesmen will invent cheap lies, putting the blame upon
    the nation that is attacked, and every man will be glad of those
    conscience-soothing falsities, and will diligently study them, and refuse
    to examine any refutations of them; and thus he will by and by convince
    himself that the war is just, and will thank God for the better sleep
    he enjoys after this process of grotesque self-deception." -- Mark Twain
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