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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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