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Subject[PATCH v3 01/32] PCI: add pcie_flags_reg into struct pci_dev to cache PCIe capabilities register
Date
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 | 3 ++-
include/linux/pci.h | 10 ++++++++++
2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 6c143b4..ba4d855 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -929,7 +929,8 @@ 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_type = (reg16 & PCI_EXP_FLAGS_TYPE) >> 4;
+ pdev->pcie_flags_reg = reg16;
+ pdev->pcie_type = pci_pcie_type(pdev);
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..95662b2 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_reg; /* cached PCI-E Capabilities Register */

struct pci_driver *driver; /* which driver has allocated this device */
u64 dma_mask; /* Mask of the bits of bus address this
@@ -1650,6 +1651,15 @@ static inline bool pci_is_pcie(struct pci_dev *dev)
return !!pci_pcie_cap(dev);
}

+/**
+ * pci_pcie_type - get the PCIe device/port type
+ * @dev: PCI device
+ */
+static inline int pci_pcie_type(const struct pci_dev *dev)
+{
+ return (dev->pcie_flags_reg & PCI_EXP_FLAGS_TYPE) >> 4;
+}
+
void pci_request_acs(void);
bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags);
bool pci_acs_path_enabled(struct pci_dev *start,
--
1.7.9.5


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