linux-kernel - [PATCH 3/5] PCI: mediatek-gen3: Disable ASPM L0s

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Message-ID: <20250103060035.30688-4-jianjun.wang@mediatek.com>
Date: Fri, 3 Jan 2025 14:00:13 +0800
From: Jianjun Wang <jianjun.wang@...iatek.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>, Lorenzo Pieralisi
	<lpieralisi@...nel.org>, Krzysztof Wilczyński
	<kw@...ux.com>, Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, Rob
 Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor
 Dooley <conor+dt@...nel.org>, Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
CC: Ryder Lee <ryder.lee@...iatek.com>, Jianjun Wang
	<jianjun.wang@...iatek.com>, <linux-pci@...r.kernel.org>,
	<linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	Xavier Chang <Xavier.Chang@...iatek.com>
Subject: [PATCH 3/5] PCI: mediatek-gen3: Disable ASPM L0s

Disable ASPM L0s support because it does not significantly save power
but impacts performance.

Signed-off-by: Jianjun Wang <jianjun.wang@...iatek.com>
---
 drivers/pci/controller/pcie-mediatek-gen3.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
index ed3c0614486c..4bd3b39eebe2 100644
--- a/drivers/pci/controller/pcie-mediatek-gen3.c
+++ b/drivers/pci/controller/pcie-mediatek-gen3.c
@@ -84,6 +84,9 @@
 #define PCIE_MSI_SET_ENABLE_REG		0x190
 #define PCIE_MSI_SET_ENABLE		GENMASK(PCIE_MSI_SET_NUM - 1, 0)
 
+#define PCIE_LOW_POWER_CTRL_REG		0x194
+#define PCIE_FORCE_DIS_L0S		BIT(8)
+
 #define PCIE_PIPE4_PIE8_REG		0x338
 #define PCIE_K_FINETUNE_MAX		GENMASK(5, 0)
 #define PCIE_K_FINETUNE_ERR		GENMASK(7, 6)
@@ -458,6 +461,14 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
 	val &= ~PCIE_INTX_ENABLE;
 	writel_relaxed(val, pcie->base + PCIE_INT_ENABLE_REG);
 
+	/*
+	 * Disable L0s support because it does not significantly save power
+	 * but impacts performance.
+	 */
+	val = readl_relaxed(pcie->base + PCIE_LOW_POWER_CTRL_REG);
+	val |= PCIE_FORCE_DIS_L0S;
+	writel_relaxed(val, pcie->base + PCIE_LOW_POWER_CTRL_REG);
+
 	/* Disable DVFSRC voltage request */
 	val = readl_relaxed(pcie->base + PCIE_MISC_CTRL_REG);
 	val |= PCIE_DISABLE_DVFSRC_VLT_REQ;
-- 
2.46.0