linux-kernel - [PATCH v4 08/13] PCI: dw-rockchip: Refactor code by using dw_pcie_clear_and_set

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Message-Id: <20250813044531.180411-9-18255117159@163.com>
Date: Wed, 13 Aug 2025 12:45:26 +0800
From: Hans Zhang <18255117159@....com>
To: lpieralisi@...nel.org,
	bhelgaas@...gle.com,
	mani@...nel.org,
	kwilczynski@...nel.org
Cc: robh@...nel.org,
	jingoohan1@...il.com,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Hans Zhang <18255117159@....com>
Subject: [PATCH v4 08/13] PCI: dw-rockchip: Refactor code by using dw_pcie_clear_and_set_dword()

Rockchip PCIe driver implements L0s capability enablement through
explicit register read-modify-write. The current approach reads the
LNKCAP register, modifies the ASPM_L0S bit, then writes back the
value with DBI write protection handling.

Refactor ASPM capability configuration using
dw_pcie_clear_and_set_dword(). The helper combines bit manipulation with
DBI protection in a single call, replacing three-step manual operations.
This simplifies the capability setup flow and reduces code complexity.

Adopting the standard helper improves maintainability by eliminating
local variables and explicit bitwise operations. The change also ensures
consistent handling of DBI write protection across capability modification
functions.

Signed-off-by: Hans Zhang <18255117159@....com>
---
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index b5f5eee5a50e..a49cf89e5e08 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -196,15 +196,14 @@ static bool rockchip_pcie_link_up(struct dw_pcie *pci)

 static void rockchip_pcie_enable_l0s(struct dw_pcie *pci)
 {
-	u32 cap, lnkcap;
+	u32 cap;

 	/* Enable L0S capability for all SoCs */
 	cap = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
 	if (cap) {
-		lnkcap = dw_pcie_readl_dbi(pci, cap + PCI_EXP_LNKCAP);
-		lnkcap |= PCI_EXP_LNKCAP_ASPM_L0S;
 		dw_pcie_dbi_ro_wr_en(pci);
-		dw_pcie_writel_dbi(pci, cap + PCI_EXP_LNKCAP, lnkcap);
+		dw_pcie_clear_and_set_dword(pci, cap + PCI_EXP_LNKCAP,
+					    0, PCI_EXP_LNKCAP_ASPM_L0S);
 		dw_pcie_dbi_ro_wr_dis(pci);
 	}
 }
-- 
2.25.1