linux-kernel - [PATCH v2 2/2] PCI: Remove redundant MPS configuration

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Message-Id: <20250425095708.32662-3-18255117159@163.com>
Date: Fri, 25 Apr 2025 17:57:08 +0800
From: Hans Zhang <18255117159@....com>
To: lpieralisi@...nel.org,
	kw@...ux.com,
	bhelgaas@...gle.com,
	heiko@...ech.de,
	thomas.petazzoni@...tlin.com,
	manivannan.sadhasivam@...aro.org,
	yue.wang@...ogic.com
Cc: pali@...nel.org,
	neil.armstrong@...aro.org,
	robh@...nel.org,
	jingoohan1@...il.com,
	khilman@...libre.com,
	jbrunet@...libre.com,
	martin.blumenstingl@...glemail.com,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-amlogic@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org,
	Hans Zhang <18255117159@....com>
Subject: [PATCH v2 2/2] PCI: Remove redundant MPS configuration

With the PCI core now centrally configuring root port MPS to
hardware-supported maximums (via 128 << pcie_mpss) during host probing,
platform-specific MPS adjustments are redundant. This patch removes the
custom the configuration of the max payload logic to align with the
standardized initialization flow.

By eliminating redundant code, this change prevents conflicts with global
PCIe hierarchy tuning policies and reduces maintenance overhead. The Meson
driver now fully relies on the core PCI framework for MPS configuration,
ensuring consistency across the PCIe topology while preserving
hardware-specific MRRS handling.

Signed-off-by: Hans Zhang <18255117159@....com>
---
 drivers/pci/controller/dwc/pci-meson.c | 17 -----------------
 drivers/pci/controller/pci-aardvark.c  |  2 --
 2 files changed, 19 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
index db9482a113e9..126f38ed453d 100644
--- a/drivers/pci/controller/dwc/pci-meson.c
+++ b/drivers/pci/controller/dwc/pci-meson.c
@@ -261,22 +261,6 @@ static int meson_size_to_payload(struct meson_pcie *mp, int size)
 	return fls(size) - 8;
 }
 
-static void meson_set_max_payload(struct meson_pcie *mp, int size)
-{
-	struct dw_pcie *pci = &mp->pci;
-	u32 val;
-	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
-	int max_payload_size = meson_size_to_payload(mp, size);
-
-	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_DEVCTL);
-	val &= ~PCI_EXP_DEVCTL_PAYLOAD;
-	dw_pcie_writel_dbi(pci, offset + PCI_EXP_DEVCTL, val);
-
-	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_DEVCTL);
-	val |= PCIE_CAP_MAX_PAYLOAD_SIZE(max_payload_size);
-	dw_pcie_writel_dbi(pci, offset + PCI_EXP_DEVCTL, val);
-}
-
 static void meson_set_max_rd_req_size(struct meson_pcie *mp, int size)
 {
 	struct dw_pcie *pci = &mp->pci;
@@ -381,7 +365,6 @@ static int meson_pcie_host_init(struct dw_pcie_rp *pp)
 
 	pp->bridge->ops = &meson_pci_ops;
 
-	meson_set_max_payload(mp, MAX_PAYLOAD_SIZE);
 	meson_set_max_rd_req_size(mp, MAX_READ_REQ_SIZE);
 
 	return 0;
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index a29796cce420..d8852892994a 100644
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -549,9 +549,7 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
 	reg = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + PCI_EXP_DEVCTL);
 	reg &= ~PCI_EXP_DEVCTL_RELAX_EN;
 	reg &= ~PCI_EXP_DEVCTL_NOSNOOP_EN;
-	reg &= ~PCI_EXP_DEVCTL_PAYLOAD;
 	reg &= ~PCI_EXP_DEVCTL_READRQ;
-	reg |= PCI_EXP_DEVCTL_PAYLOAD_512B;
 	reg |= PCI_EXP_DEVCTL_READRQ_512B;
 	advk_writel(pcie, reg, PCIE_CORE_PCIEXP_CAP + PCI_EXP_DEVCTL);
 
-- 
2.25.1