Messages in this thread | | | Date | Wed, 30 Sep 2015 16:01:19 -0700 | From | David Daney <> | Subject | Re: [PATCH v3 2/2] PCI: Add support for Enhanced Allocation devices |
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On 09/30/2015 03:50 PM, Sean O. Stalley wrote: > On Tue, Sep 29, 2015 at 04:53:20PM -0700, David Daney wrote: >> On 09/29/2015 03:47 PM, Sean O. Stalley wrote: >> [...] >>>>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >>>>>> index 6a9a111..7c60b16 100644 >>>>>> --- a/drivers/pci/pci.c >>>>>> +++ b/drivers/pci/pci.c >>>>>> @@ -2148,6 +2148,284 @@ void pci_pm_init(struct pci_dev *dev) >>>>>> } >>>>>> } >>>>>> >>>>>> +static unsigned long pci_ea_set_flags(struct pci_dev *dev, u8 prop) >>>>>> +{ >>>>>> + unsigned long flags = IORESOURCE_PCI_FIXED | IORESOURCE_SIZEALIGN; >>>>> >>>>> Why did you add the IORESOURCE_SIZEALIGN flag? EA allows for unaligned resources. >>>> >>>> pci_bus_assign_resources() fails causing the devices to be unusable >>>> if resource_alignment() returns zero. The easiest fix for this was >>>> to specify IORESOURCE_SIZEALIGN. >>>> >>>> An alternative would be to change the code in setup-bus.c so that >>>> for IORESOURCE_PCI_FIXED resources, it didn't barf. >>> >>> I would do this alternative, but with a IORESOURCE_PCI_EA flag. >>> >> >> I don't think we need IORESOURCE_PCI_EA. If a resource is tagged as >> IORESOURCE_PCI_FIXED that means that it cannot be changed, we >> shouldn't care why it is fixed (due to an EA capability for >> example). We just need to gracefully handle IORESOURCE_PCI_FIXED in >> the places where things currently go wrong. >> >> David Daney >> > > I agree that we need to make sure fixed things stay fixed, > regardless of if they are fixed by EA or something else. > > The question is: do we want to allow all fixed resources to be non-aligned, or just EA?
The alignment should only be important if a new address is being calculated for a BAR or behind the bridge memory/io region. If the resource is fixed, I would almost say that "alignment" is an undefined concept. So, in the places were we need special treatment for IORESOURCE_PCI_FIXED, I would argue that we shouldn't be use the resource alignment information.
David Daney
> > -Sean >
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