[PATCH 0/3] PCI: dwc: Cache PCIe capability offset and simplify drivers

Hans Zhang <[email protected]> Sat, 9 May 2026 21:51:49 +0800
Newsgroups dev.linux.lists.sophgo,dev.linux.lists.spacemit,org.infradead.lists.linux-amlogic,org.infradead.lists.linux-riscv,org.infradead.lists.linux-rockchip,org.kernel.vger.linux-arm-msm,org.kernel.vger.linux-kernel,org.kernel.vger.linux-pci,org.kernel.vger.linux-tegra,org.ozlabs.lists.linuxppc-dev
Message-ID <[email protected]>
The DWC PCIe core and its many platform drivers repeatedly call
dw_pcie_find_capability(pci, PCI_CAP_ID_EXP) to obtain the offset of the
PCI Express Capability structure. This is wasteful and makes the code
verbose. And some even search for the PCI_CAP_ID_EXP offset value within
the suspend/resume functions.

Add a cached pcie_cap field in struct dw_pcie and a helper
dw_pcie_get_pcie_cap() to initialize it once at probe time. Then replace
all explicit capability searches with the cached value across the
entire dwc subtree.

Hans Zhang (3):
  PCI: dwc: Add pcie_cap field and helper in designware header
  PCI: dwc: Use cached PCIe capability offset in core
  PCI: dwc: Simplify platform drivers using cached capability offset

 drivers/pci/controller/dwc/pci-imx6.c         |  6 +--
 .../pci/controller/dwc/pci-layerscape-ep.c    |  4 +-
 drivers/pci/controller/dwc/pci-meson.c        |  4 +-
 .../pci/controller/dwc/pcie-designware-ep.c   |  4 +-
 .../pci/controller/dwc/pcie-designware-host.c |  4 +-
 drivers/pci/controller/dwc/pcie-designware.c  | 16 +++---
 drivers/pci/controller/dwc/pcie-designware.h  | 17 +++++++
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 15 +++---
 drivers/pci/controller/dwc/pcie-eswin.c       |  3 +-
 drivers/pci/controller/dwc/pcie-fu740.c       |  2 +-
 drivers/pci/controller/dwc/pcie-intel-gw.c    |  2 +-
 drivers/pci/controller/dwc/pcie-qcom-ep.c     | 11 ++--
 drivers/pci/controller/dwc/pcie-qcom.c        | 24 ++++-----
 drivers/pci/controller/dwc/pcie-sophgo.c      |  8 ++-
 drivers/pci/controller/dwc/pcie-spacemit-k1.c |  5 +-
 drivers/pci/controller/dwc/pcie-spear13xx.c   |  6 +--
 drivers/pci/controller/dwc/pcie-tegra194.c    | 51 +++++++------------
 17 files changed, 85 insertions(+), 97 deletions(-)


base-commit: 70390501d1944d4e5b8f7352be180fceb3a44132
-- 
2.34.1