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

From: David Daney
Date: Wed Sep 30 2015 - 19:02:03 EST

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)

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

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


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at