From d45736b5984954da71292d858f277bac9c70cd2e Mon Sep 17 00:00:00 2001 From: Shashank Babu Chinta Venkata Date: Wed, 11 Sep 2024 20:56:28 +0530 Subject: PCI: qcom: Add equalization settings for 16.0 GT/s MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit During high data transmission rates such as 16.0 GT/s, there is an increased risk of signal loss due to poor channel quality and interference. This can impact receiver's ability to capture signals accurately. Hence, as signal compensation is achieved through appropriate lane equalization, apply lane equalization settings at both transmitter and receiver which results in an increase in the PCIe signal strength. While at it, modify the pcie-tegra194 driver to make use of the common GEN3_EQ_CONTROL_OFF definitions in pcie-designware.h. Link: https://lore.kernel.org/linux-pci/20240911-pci-qcom-gen4-stability-v7-3-743f5c1fd027@linaro.org Tested-by: Johan Hovold Signed-off-by: Shashank Babu Chinta Venkata [mani: dropped the code refactoring and minor changes] Signed-off-by: Manivannan Sadhasivam [kwilczynski: commit log] Signed-off-by: Krzysztof Wilczyński Reviewed-by: Johan Hovold Reviewed-by: Manivannan Sadhasivam --- drivers/pci/controller/dwc/pcie-qcom-common.c | 47 +++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 drivers/pci/controller/dwc/pcie-qcom-common.c (limited to 'drivers/pci/controller/dwc/pcie-qcom-common.c') diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.c b/drivers/pci/controller/dwc/pcie-qcom-common.c new file mode 100644 index 000000000000..596a35449de1 --- /dev/null +++ b/drivers/pci/controller/dwc/pcie-qcom-common.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved. + */ + +#include + +#include "pcie-designware.h" +#include "pcie-qcom-common.h" + +void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci) +{ + u32 reg; + + /* + * GEN3_RELATED_OFF register is repurposed to apply equalization + * settings at various data transmission rates through registers namely + * GEN3_EQ_*. The RATE_SHADOW_SEL bit field of GEN3_RELATED_OFF + * determines the data rate for which these equalization settings are + * applied. + */ + reg = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF); + reg &= ~GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL; + reg &= ~GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK; + reg |= FIELD_PREP(GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK, + GEN3_RELATED_OFF_RATE_SHADOW_SEL_16_0GT); + dw_pcie_writel_dbi(pci, GEN3_RELATED_OFF, reg); + + reg = dw_pcie_readl_dbi(pci, GEN3_EQ_FB_MODE_DIR_CHANGE_OFF); + reg &= ~(GEN3_EQ_FMDC_T_MIN_PHASE23 | + GEN3_EQ_FMDC_N_EVALS | + GEN3_EQ_FMDC_MAX_PRE_CUSROR_DELTA | + GEN3_EQ_FMDC_MAX_POST_CUSROR_DELTA); + reg |= FIELD_PREP(GEN3_EQ_FMDC_T_MIN_PHASE23, 0x1) | + FIELD_PREP(GEN3_EQ_FMDC_N_EVALS, 0xd) | + FIELD_PREP(GEN3_EQ_FMDC_MAX_PRE_CUSROR_DELTA, 0x5) | + FIELD_PREP(GEN3_EQ_FMDC_MAX_POST_CUSROR_DELTA, 0x5); + dw_pcie_writel_dbi(pci, GEN3_EQ_FB_MODE_DIR_CHANGE_OFF, reg); + + reg = dw_pcie_readl_dbi(pci, GEN3_EQ_CONTROL_OFF); + reg &= ~(GEN3_EQ_CONTROL_OFF_FB_MODE | + GEN3_EQ_CONTROL_OFF_PHASE23_EXIT_MODE | + GEN3_EQ_CONTROL_OFF_FOM_INC_INITIAL_EVAL | + GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC); + dw_pcie_writel_dbi(pci, GEN3_EQ_CONTROL_OFF, reg); +} +EXPORT_SYMBOL_GPL(qcom_pcie_common_set_16gt_equalization); -- cgit v1.2.3-70-g09d2 From d14bc28af34fb8b599c1cc4ce24a2833e60ade8f Mon Sep 17 00:00:00 2001 From: Shashank Babu Chinta Venkata Date: Wed, 11 Sep 2024 20:56:29 +0530 Subject: PCI: qcom: Add RX lane margining settings for 16.0 GT/s MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. Link: https://lore.kernel.org/linux-pci/20240911-pci-qcom-gen4-stability-v7-4-743f5c1fd027@linaro.org Tested-by: Johan Hovold Signed-off-by: Shashank Babu Chinta Venkata [mani: dropped the code refactoring and minor changes] Signed-off-by: Manivannan Sadhasivam [kwilczynski: commit log] Signed-off-by: Krzysztof Wilczyński Reviewed-by: Johan Hovold Reviewed-by: Manivannan Sadhasivam --- 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(-) (limited to 'drivers/pci/controller/dwc/pcie-qcom-common.c') diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h index 67cc2677ab2e..347ab74ac35a 100644 --- a/drivers/pci/controller/dwc/pcie-designware.h +++ b/drivers/pci/controller/dwc/pcie-designware.h @@ -210,6 +210,24 @@ #define PCIE_PL_CHK_REG_ERR_ADDR 0xB28 +/* + * 16.0 GT/s (Gen 4) 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 596a35449de1..3aad19b56da8 100644 --- a/drivers/pci/controller/dwc/pcie-qcom-common.c +++ b/drivers/pci/controller/dwc/pcie-qcom-common.c @@ -45,3 +45,34 @@ void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci) dw_pcie_writel_dbi(pci, GEN3_EQ_CONTROL_OFF, reg); } EXPORT_SYMBOL_GPL(qcom_pcie_common_set_16gt_equalization); + +void qcom_pcie_common_set_16gt_lane_margining(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_lane_margining); diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h index 536387e02e29..7d88d29e4766 100644 --- a/drivers/pci/controller/dwc/pcie-qcom-common.h +++ b/drivers/pci/controller/dwc/pcie-qcom-common.h @@ -9,5 +9,6 @@ struct dw_pcie; void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci); +void qcom_pcie_common_set_16gt_lane_margining(struct dw_pcie *pci); #endif diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c index 310d52393392..aa8443c995e7 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_equalization(pci); + qcom_pcie_common_set_16gt_lane_margining(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 1e84366ac0bb..22028d10b994 100644 --- a/drivers/pci/controller/dwc/pcie-qcom.c +++ b/drivers/pci/controller/dwc/pcie-qcom.c @@ -296,8 +296,10 @@ 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_equalization(pci); + qcom_pcie_common_set_16gt_lane_margining(pci); + } /* Enable Link Training state machine */ if (pcie->cfg->ops->ltssm_enable) -- cgit v1.2.3-70-g09d2