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SubjectRe: [RFC PATCH 01/14] PCI: add pcie_flags into struct pci_dev to cache PCIe capabilities register
On Tue, 10 Jul 2012 23:54:02 +0800
Jiang Liu <liuj97@gmail.com> wrote:

> From: Yijing Wang <wangyijing@huawei.com>
>
> From: Yijing Wang <wangyijing@huawei.com>
>
> Since PCI Express Capabilities Register is read only, cache its value
> into struct pci_dev to avoid repeatedly calling pci_read_config_*().
>
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> Signed-off-by: Jiang Liu <liuj97@gmail.com>
> ---
> drivers/pci/probe.c | 1 +
> include/linux/pci.h | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 6c143b4..65e82e3 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -929,6 +929,7 @@ void set_pcie_port_type(struct pci_dev *pdev)
> pdev->is_pcie = 1;
> pdev->pcie_cap = pos;
> pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
> + pdev->pcie_flags = reg16;
> pdev->pcie_type = (reg16 & PCI_EXP_FLAGS_TYPE) >> 4;
> pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, &reg16);
> pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 5faa831..f4a7ad6 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -258,6 +258,7 @@ struct pci_dev {
> u8 pcie_mpss:3; /* PCI-E Max Payload Size Supported */
> u8 rom_base_reg; /* which config register controls the ROM */
> u8 pin; /* which interrupt pin this device uses */
> + u16 pcie_flags; /* cached PCI-E Capabilities Register */

"xxx_flags" sounds like a bit flag. This variable stores a value of PCIe capability
register, doesn't it? How about "pcie_cap_reg" ?

>
> struct pci_driver *driver; /* which driver has allocated this device */
> u64 dma_mask; /* Mask of the bits of bus address this
> --
> 1.7.9.5
>
> --
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--
Taku Izumi <izumi.taku@jp.fujitsu.com>



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