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Message-Id: <20240904-pci-qcom-gen4-stability-v6-4-ec39f7ae3f62@linaro.org>
Date: Wed, 04 Sep 2024 12:42:00 +0530
From: Manivannan Sadhasivam via B4 Relay <devnull+manivannan.sadhasivam.linaro.org@...nel.org>
To: Richard Zhu <hongxing.zhu@....com>,
Lucas Stach <l.stach@...gutronix.de>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Fabio Estevam <festevam@...il.com>, Jingoo Han <jingoohan1@...il.com>,
Chuanhua Lei <lchuanhua@...linear.com>,
Marek Vasut <marek.vasut+renesas@...il.com>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Cc: linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
imx@...ts.linux.dev, linux-kernel@...r.kernel.org,
linux-renesas-soc@...r.kernel.org, linux-arm-msm@...r.kernel.org,
abel.vesa@...aro.org, johan+linaro@...nel.org,
Shashank Babu Chinta Venkata <quic_schintav@...cinc.com>,
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH v6 4/4] PCI: qcom: Add RX margining settings for 16.0 GT/s
From: Shashank Babu Chinta Venkata <quic_schintav@...cinc.com>
Add RX lane margining settings for 16.0 GT/s (GEN 4) data rate. These
settings improve link stability while operating at high date rates and
helps to improve signal quality.
Signed-off-by: Shashank Babu Chinta Venkata <quic_schintav@...cinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
[mani: dropped the code refactoring and minor changes]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
drivers/pci/controller/dwc/pcie-designware.h | 18 ++++++++++++++++
drivers/pci/controller/dwc/pcie-qcom-common.c | 31 +++++++++++++++++++++++++++
drivers/pci/controller/dwc/pcie-qcom-common.h | 1 +
drivers/pci/controller/dwc/pcie-qcom-ep.c | 4 +++-
drivers/pci/controller/dwc/pcie-qcom.c | 4 +++-
5 files changed, 56 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 51744ad25575..f5be99731f7e 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -209,6 +209,24 @@
#define PCIE_PL_CHK_REG_ERR_ADDR 0xB28
+/*
+ * 16.0 GT/s (GEN4) lane margining register definitions
+ */
+#define GEN4_LANE_MARGINING_1_OFF 0xb80
+#define MARGINING_MAX_VOLTAGE_OFFSET GENMASK(29, 24)
+#define MARGINING_NUM_VOLTAGE_STEPS GENMASK(22, 16)
+#define MARGINING_MAX_TIMING_OFFSET GENMASK(13, 8)
+#define MARGINING_NUM_TIMING_STEPS GENMASK(5, 0)
+
+#define GEN4_LANE_MARGINING_2_OFF 0xb84
+#define MARGINING_IND_ERROR_SAMPLER BIT(28)
+#define MARGINING_SAMPLE_REPORTING_METHOD BIT(27)
+#define MARGINING_IND_LEFT_RIGHT_TIMING BIT(26)
+#define MARGINING_IND_UP_DOWN_VOLTAGE BIT(25)
+#define MARGINING_VOLTAGE_SUPPORTED BIT(24)
+#define MARGINING_MAXLANES GENMASK(20, 16)
+#define MARGINING_SAMPLE_RATE_TIMING GENMASK(13, 8)
+#define MARGINING_SAMPLE_RATE_VOLTAGE GENMASK(5, 0)
/*
* iATU Unroll-specific register definitions
* From 4.80 core version the address translation will be made by unroll
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.c b/drivers/pci/controller/dwc/pcie-qcom-common.c
index dc7d93db9dc5..99b75e7f085d 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
@@ -43,3 +43,34 @@ void qcom_pcie_common_set_16gt_eq_settings(struct dw_pcie *pci)
dw_pcie_writel_dbi(pci, GEN3_EQ_CONTROL_OFF, reg);
}
EXPORT_SYMBOL_GPL(qcom_pcie_common_set_16gt_eq_settings);
+
+void qcom_pcie_common_set_16gt_rx_margining_settings(struct dw_pcie *pci)
+{
+ u32 reg;
+
+ reg = dw_pcie_readl_dbi(pci, GEN4_LANE_MARGINING_1_OFF);
+ reg &= ~(MARGINING_MAX_VOLTAGE_OFFSET |
+ MARGINING_NUM_VOLTAGE_STEPS |
+ MARGINING_MAX_TIMING_OFFSET |
+ MARGINING_NUM_TIMING_STEPS);
+ reg |= FIELD_PREP(MARGINING_MAX_VOLTAGE_OFFSET, 0x24) |
+ FIELD_PREP(MARGINING_NUM_VOLTAGE_STEPS, 0x78) |
+ FIELD_PREP(MARGINING_MAX_TIMING_OFFSET, 0x32) |
+ FIELD_PREP(MARGINING_NUM_TIMING_STEPS, 0x10);
+ dw_pcie_writel_dbi(pci, GEN4_LANE_MARGINING_1_OFF, reg);
+
+ reg = dw_pcie_readl_dbi(pci, GEN4_LANE_MARGINING_2_OFF);
+ reg |= MARGINING_IND_ERROR_SAMPLER |
+ MARGINING_SAMPLE_REPORTING_METHOD |
+ MARGINING_IND_LEFT_RIGHT_TIMING |
+ MARGINING_VOLTAGE_SUPPORTED;
+ reg &= ~(MARGINING_IND_UP_DOWN_VOLTAGE |
+ MARGINING_MAXLANES |
+ MARGINING_SAMPLE_RATE_TIMING |
+ MARGINING_SAMPLE_RATE_VOLTAGE);
+ reg |= FIELD_PREP(MARGINING_MAXLANES, pci->num_lanes) |
+ FIELD_PREP(MARGINING_SAMPLE_RATE_TIMING, 0x3f) |
+ FIELD_PREP(MARGINING_SAMPLE_RATE_VOLTAGE, 0x3f);
+ dw_pcie_writel_dbi(pci, GEN4_LANE_MARGINING_2_OFF, reg);
+}
+EXPORT_SYMBOL_GPL(qcom_pcie_common_set_16gt_rx_margining_settings);
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
index 259e04b7bdf9..e9ddc901082e 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.h
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
@@ -6,3 +6,4 @@
#include "pcie-designware.h"
void qcom_pcie_common_set_16gt_eq_settings(struct dw_pcie *pci);
+void qcom_pcie_common_set_16gt_rx_margining_settings(struct dw_pcie *pci);
diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index af83470216e8..5c220f2ecafe 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -487,8 +487,10 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
goto err_disable_resources;
}
- if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT)
+ if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT) {
qcom_pcie_common_set_16gt_eq_settings(pci);
+ qcom_pcie_common_set_16gt_rx_margining_settings(pci);
+ }
/*
* The physical address of the MMIO region which is exposed as the BAR
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 2742e82fdcb3..b0b1d8d34279 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -284,8 +284,10 @@ static int qcom_pcie_start_link(struct dw_pcie *pci)
{
struct qcom_pcie *pcie = to_qcom_pcie(pci);
- if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT)
+ if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT) {
qcom_pcie_common_set_16gt_eq_settings(pci);
+ qcom_pcie_common_set_16gt_rx_margining_settings(pci);
+ }
/* Enable Link Training state machine */
if (pcie->cfg->ops->ltssm_enable)
--
2.25.1
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