linux-kernel - Re: [PATCH 2/2] PCI: Add support for Enhanced Allocation devices

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Date:	Tue, 1 Sep 2015 16:14:08 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	"Sean O. Stalley" <sean.stalley@...el.com>
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 2/2] PCI: Add support for Enhanced Allocation devices

On Thu, Aug 20, 2015 at 9:59 AM, Sean O. Stalley <sean.stalley@...el.com> wrote:
> Add support for devices using Enhanced Allocation entries instead of BARs.
> This patch allows the kernel to parse the EA Extended Capability structure
> in PCI configspace and claim the BAR-equivalent resources.
>
> Signed-off-by: Sean O. Stalley <sean.stalley@...el.com>
> ---
>  drivers/pci/pci.c   | 219 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/pci/pci.h   |   1 +
>  drivers/pci/probe.c |   3 +
>  3 files changed, 223 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 0008c95..c8217a8 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
...
> +
> +/* Read an Enhanced Allocation (EA) entry */
> +static int pci_ea_read(struct pci_dev *dev, int offset)
> +{
...
> +       res->name = pci_name(dev);
> +       res->start = start;
> +       res->end = end;
> +       res->flags = flags;
> +
> +       pci_ea_claim_resource(dev, res);
> +
> +out:
> +       return offset + ent_size;
> +}
> +
> +/* Enhanced Allocation Initalization */
> +void pci_ea_init(struct pci_dev *dev)
> +{
...
> +
> +       for (i = 0; i < num_ent; ++i) {
> +               /* parse each EA entry */
> +               dev_dbg(&dev->dev, "%s: parsing entry %i...\n", __func__, i);
> +               offset = pci_ea_read(dev, offset);
> +       }
> +}
> +
>  static void pci_add_saved_cap(struct pci_dev *pci_dev,
>         struct pci_cap_saved_state *new_cap)
>  {

> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index cefd636..4cadf35 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1522,6 +1522,9 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
>
>  static void pci_init_capabilities(struct pci_dev *dev)
>  {
> +       /* Enhanced Allocation */
> +       pci_ea_init(dev);
> +
>         /* MSI/MSI-X list */
>         pci_msi_init_pci_dev(dev);
>

Should not call pci_ea_claim_resource() that early.

For x86 and other arches, we call
pcibios_resource_survey/pcibios_allocate_bus_resouce/pcibios_allocate_resources
quite late.

Yinghai
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