[RFC PATCH 01/14] PCI: add pcie_flags into struct pci_dev to cache PCIe capabilities register

[Jiang Liu]

From: Yijing Wang <wangyijing@xxxxxxxxxx>

From: Yijing Wang <wangyijing@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Jiang Liu <liuj97@xxxxxxxxx>
---
 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 */
 
 	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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