linux-kernel - [PATCH v2 09/13] PCI: fu740: Refactor code by using dw_pcie_clear_and_set

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Message-Id: <20250618152112.1010147-10-18255117159@163.com>
Date: Wed, 18 Jun 2025 23:21:08 +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 v2 09/13] PCI: fu740: Refactor code by using dw_pcie_clear_and_set_dword()

SiFive FU740 PCIe driver uses direct register write to initiate link speed
change after setting target link capabilities. The current implementation
sets PORT_LOGIC_SPEED_CHANGE bit via explicit read-modify-write sequence.

Replace manual bit manipulation with dw_pcie_clear_and_set_dword() for
speed change initiation. The helper encapsulates read-modify-write
operations while providing clear intent through "clear 0, set BIT" usage.

This refactoring aligns the driver with standard DesignWare programming
patterns and reduces code complexity. The change also ensures consistent
handling of speed change initiation across all DesignWare base
controllers.

Signed-off-by: Hans Zhang <18255117159@....com>
---
 drivers/pci/controller/dwc/pcie-fu740.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-fu740.c b/drivers/pci/controller/dwc/pcie-fu740.c
index 66367252032b..8210ff1fd91e 100644
--- a/drivers/pci/controller/dwc/pcie-fu740.c
+++ b/drivers/pci/controller/dwc/pcie-fu740.c
@@ -216,9 +216,8 @@ static int fu740_pcie_start_link(struct dw_pcie *pci)
 		tmp |= orig;
 		dw_pcie_writel_dbi(pci, cap_exp + PCI_EXP_LNKCAP, tmp);

-		tmp = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
-		tmp |= PORT_LOGIC_SPEED_CHANGE;
-		dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, tmp);
+		dw_pcie_clear_and_set_dword(pci, PCIE_LINK_WIDTH_SPEED_CONTROL,
+					    0, PORT_LOGIC_SPEED_CHANGE);

 		ret = dw_pcie_wait_for_link(pci);
 		if (ret) {
-- 
2.25.1