Re: [PATCH v3 2/2] PCI: Add support for Enhanced Allocation devices

[David Daney]

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

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