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    SubjectRe: [PATCH] PCI: Always set prefetchable base/limit upper32 registers
    Alex Williamson wrote:
    > On Mon, 2009-11-30 at 13:52 -0800, Yinghai Lu wrote:
    >> Alex Williamson wrote:
    >>> On Mon, 2009-11-30 at 13:36 -0800, Yinghai Lu wrote:
    >>>> Alex Williamson wrote:
    >>>>> - if (pref_mem64) {
    >>>>> - /* Set the upper 32 bits of PREF base & limit. */
    >>>>> - pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, bu);
    >>>>> - pci_write_config_dword(bridge, PCI_PREF_LIMIT_UPPER32, lu);
    >>>>> - }
    >>>>> + /* Set the upper 32 bits of PREF base & limit. */
    >>>>> + pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, bu);
    >>>>> + pci_write_config_dword(bridge, PCI_PREF_LIMIT_UPPER32, lu);
    >>>>>
    >>>>> pci_write_config_word(bridge, PCI_BRIDGE_CONTROL, bus->bridge_ctl);
    >>>>> }
    >>>> when pref_mem64=0 it means that pref register is only 32 bit, we should not touch upper 32bits.
    >>> Did you read my patch description? In that case bu = lu = 0 and we
    >>> clear whatever state the BIOS left for those registers.
    >> if HW state that reg is only 32bit pref, why should we care about the upper 32bit?
    >
    > In my case, we're programming a 32bit prefetchable range into a 64bit
    > capable bridge. We can't just assume the upper 32bits are already zero.
    >
    >> looks like that your bridge device need quirk to clear that so called upper 32bit for it.
    >
    > I don't believe the PCI spec dictates whether the upper 32bit base
    > should be 0 or -1, so it's purely a BIOS initialization choice and Linux
    > should properly handle both. If the hardware only supports 32bit
    > prefetchable windows, the hardware will drop the write, just as it did
    > for every 2.6 kernel before 1f82de10. Thanks,

    current code:

    #define PCI_PREF_RANGE_TYPE_MASK 0x0fUL
    #define PCI_PREF_RANGE_TYPE_32 0x00
    #define PCI_PREF_RANGE_TYPE_64 0x01
    #define PCI_PREF_RANGE_MASK (~0x0fUL)

    if the HW state the pref mmio is 64bit, we will touch upper 32bit. otherwise we will not touch it.

    please post your boot log to show the problem.

    YH




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