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SubjectRe: [PATCH v4 5/5] PCI: Handle Enhanced Allocation (EA) capability for bridges
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On 10/05/2015 03:54 PM, Sean O. Stalley wrote:
> On Fri, Oct 02, 2015 at 03:37:56PM -0700, David Daney wrote:
>> From: David Daney <david.daney@cavium.com>
>>
>> PCI bridges may have their properties be specified via EA entries.
>>
>> Extend the EA parser to extract the bridge resources, and modify
>> pci_read_bridge_{io,mmio,mmio_pref}() to use resources previously
>> obtained via EA.
>>
>> Save the offset to the EA capability in struct pci_dev, and use it to
>> easily find the EA bridge subordinate and secondary bus numbers.
>>
>> When assigning the bridge resources a couple of changes are required
>> so that the EA obtained IORESOURCE_PCI_FIXED are not resized, and
>> correctly linked into the resource tree.
>>
>> 1) In pbus_size_mem() do not attempt to resize the bridge resources if
>> they are marked as IORESOURCE_PCI_FIXED.
>>
>> 2) In pci_bus_alloc_from_region()for IORESOURCE_PCI_FIXED resources, just
>> try to request the resource as is, without attempting to resize it.
>>
>> Signed-off-by: David Daney <david.daney@cavium.com>
>> ---
>> drivers/pci/bus.c | 7 +++++++
>> drivers/pci/pci.c | 13 +++++++++++++
>> drivers/pci/probe.c | 31 +++++++++++++++++++++++++++++--
>> drivers/pci/setup-bus.c | 3 +++
>> include/linux/pci.h | 1 +
>> 5 files changed, 53 insertions(+), 2 deletions(-)
>> @@ -801,8 +813,23 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
>>
>> pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
>> primary = buses & 0xFF;
>> - secondary = (buses >> 8) & 0xFF;
>> - subordinate = (buses >> 16) & 0xFF;
>> + if (dev->ea_cap) {
>> + u32 dw1;
>> +
>> + pci_read_config_dword(dev, dev->ea_cap + 4, &dw1);
>> + if (dw1 & 0xFF)
>> + secondary = dw1 & 0xFF;
>> + else
>> + secondary = (buses >> 8) & 0xFF;
>> +
>> + if ((dw1 >> 8) & 0xFF)
>> + subordinate = (dw1 >> 8) & 0xFF;
>> + else
>> + subordinate = (buses >> 16) & 0xFF;
>> + } else {
>> + secondary = (buses >> 8) & 0xFF;
>> + subordinate = (buses >> 16) & 0xFF;
>> + }
>
> We can refactor this to make it cleaner/more compact. from V3 review:
>
>
> secondary = (buses >> 8) & 0xFF;
> subordinate = (buses >> 16) & 0xFF;
> if (dev->ea_cap) {
> u32 sdw;
>
> pci_read_config_dword(dev, dev->ea_cap + 4, &sdw);
>
> if (sdw & 0xFF)
> secondary = sdw & 0xFF;
>
> sdw >>= 8;
> if (sdw & 0xFF)
> subordinate = sdw & 0xFF;
> }
>

Yes, that is cleaner. I think I didn't read the comments on v3 closely
enough. I will switch to doing it this way.

Thanks,
David Daney


>
> -Sean
>


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