linux-kernel - Re: [PATCH v2 2/3] PCI: Remove PCIe Capability version checks

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Date:	Tue, 19 Nov 2013 15:04:59 -0700
From:	Myron Stowe <myron.stowe@...il.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	stable@...r.kernel.org, Myron Stowe <myron.stowe@...hat.com>,
	linux-pci <linux-pci@...r.kernel.org>,
	Amos Kong <kongjianjun@...il.com>,
	Adam Lee <adam.lee@...onical.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Yuval Mintz <yuvalmin@...adcom.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	Thomas Renninger <trenn@...e.de>
Subject: Re: [PATCH v2 2/3] PCI: Remove PCIe Capability version checks

On Tue, Nov 19, 2013 at 2:35 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> Commit c8b303d0206b28c4ff3aecada47108d1655ae00f upstream.  This is part
> of the fix for https://bugzilla.kernel.org/show_bug.cgi?id=65211
>
> Previously we relied on the PCIe r3.0, sec 7.8, spec language that says
> "For Functions that do not implement the [Link, Slot, Root] registers,
> these spaces must be hardwired to 0b," which means that for v2 PCIe
> capabilities, we don't need to check the device type at all.
>
> But it's simpler if we don't need to check the capability version at all,
> and I think the spec is explicit enough about which registers are required
> for which types that we can remove the version checks.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> Reviewed-By: Jiang Liu <jiang.liu@...wei.com>
> CC: stable@...r.kernel.org      # v3.7+
> ---
>  drivers/pci/access.c |    9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/access.c b/drivers/pci/access.c
> index e26c3bd9aca4..9a46fa9135d9 100644
> --- a/drivers/pci/access.c
> +++ b/drivers/pci/access.c
> @@ -484,8 +484,7 @@ static inline bool pcie_cap_has_lnkctl(const struct pci_dev *dev)
>  {
>         int type = pci_pcie_type(dev);
>
> -       return pcie_cap_version(dev) > 1 ||
> -              type == PCI_EXP_TYPE_ENDPOINT ||
> +       return type == PCI_EXP_TYPE_ENDPOINT ||
>                type == PCI_EXP_TYPE_LEG_END ||
>                type == PCI_EXP_TYPE_ROOT_PORT ||
>                type == PCI_EXP_TYPE_UPSTREAM ||
> @@ -498,8 +497,7 @@ static inline bool pcie_cap_has_sltctl(const struct pci_dev *dev)
>  {
>         int type = pci_pcie_type(dev);
>
> -       return pcie_cap_version(dev) > 1 ||
> -              type == PCI_EXP_TYPE_ROOT_PORT ||
> +       return type == PCI_EXP_TYPE_ROOT_PORT ||
>                (type == PCI_EXP_TYPE_DOWNSTREAM &&
>                 pcie_caps_reg(dev) & PCI_EXP_FLAGS_SLOT);
>  }
> @@ -508,8 +506,7 @@ static inline bool pcie_cap_has_rtctl(const struct pci_dev *dev)
>  {
>         int type = pci_pcie_type(dev);
>
> -       return pcie_cap_version(dev) > 1 ||
> -              type == PCI_EXP_TYPE_ROOT_PORT ||
> +       return type == PCI_EXP_TYPE_ROOT_PORT ||
>                type == PCI_EXP_TYPE_RC_EC;
>  }
>
>
> --

Acked-by: Myron Stowe <myron.stowe@...hat.com>

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