# \[PATCH v4 15/16\] PCI: dwc: tegra194: Use cached PCIe capability offset

- From: Hans Zhang \<18255117159@163.com\>
- Date: 2026-10-27 12:29:20 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2026/10/17810477
- Thread: https://ratatoskr.run/imx/2026/10/17810464/t.md

```text
Replace the two dw_pcie_find_capability(&pcie->pci, PCI_CAP_ID_EXP)
calls in tegra_pcie_dw_host_init() and pex_ep_event_pex_rst_deassert()
with dw_pcie_get_pcie_cap() so that the driver-private pcie_cap_base is
filled from the same cached value.

tegra_pcie_dw_host_init() is called from .start_link, i.e. after the
controller has been initialized, and the PERST# deassert handler runs
after the endpoint has been brought out of reset with its clocks and
power enabled. The helper therefore performs its single DBI read at the
same point as the open coded search, and the private copy keeps working
unchanged.

Signed-off-by: Hans Zhang <18255117159@163.com>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 63a0f56cad8e..965e15f55e22 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -905,8 +905,7 @@ static int tegra_pcie_dw_host_init(struct dw_pcie_rp *pp)
 	pp->bridge->ops = &tegra_pci_ops;
 
 	if (!pcie->pcie_cap_base)
-		pcie->pcie_cap_base = dw_pcie_find_capability(&pcie->pci,
-							      PCI_CAP_ID_EXP);
+		pcie->pcie_cap_base = dw_pcie_get_pcie_cap(pci);
 
 	val = dw_pcie_readl_dbi(pci, PCI_IO_BASE);
 	val &= ~(IO_BASE_IO_DECODE | IO_BASE_IO_DECODE_BIT8);
@@ -1889,8 +1888,7 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
 		dw_pcie_writel_dbi(pci, GEN3_RELATED_OFF, val);
 	}
 
-	pcie->pcie_cap_base = dw_pcie_find_capability(&pcie->pci,
-						      PCI_CAP_ID_EXP);
+	pcie->pcie_cap_base = dw_pcie_get_pcie_cap(pci);
 
 	/* Clear Slot Clock Configuration bit if SRNS configuration */
 	if (pcie->enable_srns) {
-- 
2.43.0


```