linux-kernel - Re: [PATCH v2 0/2] PCI: Add support for PCI Enhanced Allocation "BARs"

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Date:	Wed, 23 Sep 2015 16:51:09 -0700
From:	"Sean O. Stalley" <sean.stalley@...el.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Rajat Jain <rajatxjain@...il.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Rafał Miłecki <zajec5@...il.com>,
	"gong.chen@...ux.intel.com" <gong.chen@...ux.intel.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-api@...r.kernel.org
Subject: Re: [PATCH v2 0/2] PCI: Add support for PCI Enhanced Allocation
 "BARs"

On Wed, Sep 23, 2015 at 04:26:56PM -0700, Yinghai Lu wrote:
> On Wed, Sep 23, 2015 at 3:27 PM, Sean O. Stalley <sean.stalley@...el.com> wrote:
> > PCI Enhanced Allocation is a new method of allocating MMIO & IO
> > resources for PCI devices & bridges. It can be used instead
> > of the traditional PCI method of using BARs.
> >
> > EA entries are hardware-initialized to a fixed address.
> > Unlike BARs, regions described by EA are cannot be moved.
> > Because of this, only devices which are permanently connected to
> > the PCI bus can use EA. A removable PCI card must not use EA.
> 
> As it is fixed, can you put IORESOURCE_PCI_FIXED in the res->flags?
> 
> Thanks
> 
> Yinghai

IORESOURCE_PCI_FIXED is set in pci_ea_set_flags():
 
	+static unsigned long pci_ea_set_flags(struct pci_dev *dev, u8 prop)
	+{
	+	unsigned long flags = IORESOURCE_PCI_FIXED;
	+
	+

Which is called in pci_ea_read(), and passed to res->flags (if there aren't any errors):

	+
	+	/* Try to use primary properties, otherwise fall back to secondary */
	+	flags = pci_ea_set_flags(dev, PCI_EA_PP(dw0));
	+	if (!flags)
	+		flags = pci_ea_set_flags(dev, PCI_EA_SP(dw0));
	+

	...

	+	res->flags = flags;


-Sean
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