linux-kernel - [PATCH V4 19/22] PCI: tegra194: Add ASPM L1 entrance latency config

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Message-ID: <20260126074519.3426742-20-mmaddireddy@nvidia.com>
Date: Mon, 26 Jan 2026 13:15:16 +0530
From: Manikanta Maddireddy <mmaddireddy@...dia.com>
To: <bhelgaas@...gle.com>, <lpieralisi@...nel.org>, <kwilczynski@...nel.org>,
	<mani@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
	<conor+dt@...nel.org>, <thierry.reding@...il.com>, <jonathanh@...dia.com>,
	<jingoohan1@...il.com>, <vidyas@...dia.com>, <cassel@...nel.org>,
	<18255117159@....com>
CC: <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Manikanta
 Maddireddy" <mmaddireddy@...dia.com>
Subject: [PATCH V4 19/22] PCI: tegra194: Add ASPM L1 entrance latency config

For Tegra234, the HW PHY team conducted experiments and determined the
optimal ASPM L1 entrance latency values: 8 us for Root Port mode and
16 us for Endpoint mode. Update the default ASPM L1 entrance latency
configuration accordingly.

Signed-off-by: Manikanta Maddireddy <mmaddireddy@...dia.com>
---
V4:
* This is a new patch in this series

 drivers/pci/controller/dwc/pcie-tegra194.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index b5604b879a58..6543c6d49fc8 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -244,6 +244,8 @@ struct tegra_pcie_dw_of_data {
 	u32 cdm_chk_int_en_bit;
 	u32 gen4_preset_vec;
 	u8 n_fts[2];
+	/* L1 Latency entrance values(Rest/Prod) */
+	u32 aspm_l1_enter_lat;
 };
 
 struct tegra_pcie_dw {
@@ -714,6 +716,8 @@ static void init_host_aspm(struct tegra_pcie_dw *pcie)
 	val = dw_pcie_readl_dbi(pci, PCIE_PORT_AFR);
 	val &= ~PORT_AFR_L0S_ENTRANCE_LAT_MASK;
 	val |= (pcie->aspm_l0s_enter_lat << PORT_AFR_L0S_ENTRANCE_LAT_SHIFT);
+	val &= ~PORT_AFR_L1_ENTRANCE_LAT_MASK;
+	val |= (pcie->of_data->aspm_l1_enter_lat << PORT_AFR_L1_ENTRANCE_LAT_SHIFT);
 	val |= PORT_AFR_ENTER_ASPM;
 	dw_pcie_writel_dbi(pci, PCIE_PORT_AFR, val);
 }
@@ -2480,6 +2484,7 @@ static const struct tegra_pcie_dw_of_data tegra194_pcie_dw_rc_of_data = {
 	/* Gen4 - 5, 6, 8 and 9 presets enabled */
 	.gen4_preset_vec = 0x360,
 	.n_fts = { 52, 52 },
+	.aspm_l1_enter_lat = 3,
 };
 
 static const struct tegra_pcie_dw_of_data tegra194_pcie_dw_ep_of_data = {
@@ -2489,6 +2494,7 @@ static const struct tegra_pcie_dw_of_data tegra194_pcie_dw_ep_of_data = {
 	/* Gen4 - 5, 6, 8 and 9 presets enabled */
 	.gen4_preset_vec = 0x360,
 	.n_fts = { 52, 52 },
+	.aspm_l1_enter_lat = 3,
 };
 
 static const struct tegra_pcie_dw_of_data tegra234_pcie_dw_rc_of_data = {
@@ -2501,6 +2507,7 @@ static const struct tegra_pcie_dw_of_data tegra234_pcie_dw_rc_of_data = {
 	/* Gen4 - 6, 8 and 9 presets enabled */
 	.gen4_preset_vec = 0x340,
 	.n_fts = { 52, 80 },
+	.aspm_l1_enter_lat = 4,
 };
 
 static const struct tegra_pcie_dw_of_data tegra234_pcie_dw_ep_of_data = {
@@ -2513,6 +2520,7 @@ static const struct tegra_pcie_dw_of_data tegra234_pcie_dw_ep_of_data = {
 	/* Gen4 - 6, 8 and 9 presets enabled */
 	.gen4_preset_vec = 0x340,
 	.n_fts = { 52, 80 },
+	.aspm_l1_enter_lat = 5,
 };
 
 static const struct of_device_id tegra_pcie_dw_of_match[] = {
-- 
2.34.1