linux-kernel - [PATCH 07/13] PCI: dwc: Refactor bt1 to use dw_pcie_clear_and_set

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Message-Id: <20250611163148.860884-1-18255117159@163.com>
Date: Thu, 12 Jun 2025 00:31:48 +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 07/13] PCI: dwc: Refactor bt1 to use dw_pcie_clear_and_set_dword()

Baikal-T1 PCIe driver contains a direct register write to initiate
speed change during link training. The current implementation sets
the PORT_LOGIC_SPEED_CHANGE bit via read-modify-write without using
the standard bit manipulation helper.

Replace manual bit set operation with dw_pcie_clear_and_set_dword() to
enable speed change. The helper clearly expresses the intent to modify
a specific bit while preserving others, eliminating the need for explicit
read-before-write.

Using the standardized interface improves consistency with other
DesignWare drivers and reduces the risk of unintended bit modifications.
The change also simplifies future updates to link training logic.

Signed-off-by: Hans Zhang <18255117159@....com>
---
 drivers/pci/controller/dwc/pcie-bt1.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-bt1.c b/drivers/pci/controller/dwc/pcie-bt1.c
index 1340edc18d12..7cbaeeed033d 100644
--- a/drivers/pci/controller/dwc/pcie-bt1.c
+++ b/drivers/pci/controller/dwc/pcie-bt1.c
@@ -289,9 +289,8 @@ static int bt1_pcie_start_link(struct dw_pcie *pci)
 	 * attempt to reach a higher bus performance (up to Gen.3 - 8.0 GT/s).
 	 * This is required at least to get 8.0 GT/s speed.
 	 */
-	val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
-	val |= PORT_LOGIC_SPEED_CHANGE;
-	dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
+	dw_pcie_clear_and_set_dword(pci, PCIE_LINK_WIDTH_SPEED_CONTROL,
+				    0, PORT_LOGIC_SPEED_CHANGE);

 	ret = regmap_read_poll_timeout(btpci->sys_regs, BT1_CCU_PCIE_PMSC, val,
 				       BT1_CCU_PCIE_LTSSM_LINKUP(val),
-- 
2.25.1