From: Shashank Babu Chinta Venkata <quic_schintav@xxxxxxxxxxx>
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,
signal compensation is achieved through appropriate lane equalization
settings at both transmitter and receiver. This will result in increased
PCIe signal strength.
Signed-off-by: Shashank Babu Chinta Venkata <quic_schintav@xxxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
[mani: dropped the code refactoring and minor changes]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
MAINTAINERS | 4 ++-
drivers/pci/controller/dwc/Kconfig | 5 +++
drivers/pci/controller/dwc/Makefile | 1 +
drivers/pci/controller/dwc/pcie-designware.h | 12 +++++++
drivers/pci/controller/dwc/pcie-qcom-common.c | 45 +++++++++++++++++++++++++++
drivers/pci/controller/dwc/pcie-qcom-common.h | 8 +++++
drivers/pci/controller/dwc/pcie-qcom-ep.c | 4 +++
drivers/pci/controller/dwc/pcie-qcom.c | 4 +++
8 files changed, 82 insertions(+), 1 deletion(-)
diff --git a/MAINTAINERS b/MAINTAINERS
index f328373463b0..3cfb6068b9f0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2728,7 +2728,7 @@ F: drivers/iommu/msm*
F: drivers/mfd/ssbi.c
F: drivers/mmc/host/mmci_qcom*
F: drivers/mmc/host/sdhci-msm.c
-F: drivers/pci/controller/dwc/pcie-qcom.c
+F: drivers/pci/controller/dwc/pcie-qcom*
F: drivers/phy/qualcomm/
F: drivers/power/*/msm*
F: drivers/reset/reset-qcom-*
@@ -17757,6 +17757,7 @@ M: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
L: linux-pci@xxxxxxxxxxxxxxx
L: linux-arm-msm@xxxxxxxxxxxxxxx
S: Maintained
+F: drivers/pci/controller/dwc/pcie-qcom-common.c
F: drivers/pci/controller/dwc/pcie-qcom.c
PCIE DRIVER FOR ROCKCHIP
@@ -17793,6 +17794,7 @@ L: linux-pci@xxxxxxxxxxxxxxx
L: linux-arm-msm@xxxxxxxxxxxxxxx
S: Maintained
F: Documentation/devicetree/bindings/pci/qcom,pcie-ep.yaml
+F: drivers/pci/controller/dwc/pcie-qcom-common.c
F: drivers/pci/controller/dwc/pcie-qcom-ep.c
PCMCIA SUBSYSTEM
diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index 4c38181acffa..b6d6778b0698 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -265,12 +265,16 @@ config PCIE_DW_PLAT_EP
order to enable device-specific features PCI_DW_PLAT_EP must be
selected.
+config PCIE_QCOM_COMMON
+ bool
+
config PCIE_QCOM
bool "Qualcomm PCIe controller (host mode)"
depends on OF && (ARCH_QCOM || COMPILE_TEST)
depends on PCI_MSI
select PCIE_DW_HOST
select CRC8
+ select PCIE_QCOM_COMMON
help
Say Y here to enable PCIe controller support on Qualcomm SoCs. The
PCIe controller uses the DesignWare core plus Qualcomm-specific
@@ -281,6 +285,7 @@ config PCIE_QCOM_EP
depends on OF && (ARCH_QCOM || COMPILE_TEST)
depends on PCI_ENDPOINT
select PCIE_DW_EP
+ select PCIE_QCOM_COMMON
help
Say Y here to enable support for the PCIe controllers on Qualcomm SoCs
to work in endpoint mode. The PCIe controller uses the DesignWare core
diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
index ec215b3d6191..a8308d9ea986 100644
--- a/drivers/pci/controller/dwc/Makefile
+++ b/drivers/pci/controller/dwc/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_PCIE_SPEAR13XX) += pcie-spear13xx.o
obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone.o
obj-$(CONFIG_PCI_LAYERSCAPE) += pci-layerscape.o
obj-$(CONFIG_PCI_LAYERSCAPE_EP) += pci-layerscape-ep.o
+obj-$(CONFIG_PCIE_QCOM_COMMON) += pcie-qcom-common.o
obj-$(CONFIG_PCIE_QCOM) += pcie-qcom.o
obj-$(CONFIG_PCIE_QCOM_EP) += pcie-qcom-ep.o
obj-$(CONFIG_PCIE_ARMADA_8K) += pcie-armada8k.o
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 22765564f301..51744ad25575 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -126,6 +126,18 @@
#define GEN3_RELATED_OFF_RATE_SHADOW_SEL_SHIFT 24
#define GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK GENMASK(25, 24)
+#define GEN3_EQ_CONTROL_OFF 0x8a8
+#define GEN3_EQ_CONTROL_OFF_FB_MODE GENMASK(3, 0)
+#define GEN3_EQ_CONTROL_OFF_PHASE23_EXIT_MODE BIT(4)
+#define GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC GENMASK(23, 8)
+#define GEN3_EQ_CONTROL_OFF_FOM_INC_INITIAL_EVAL BIT(24)
+
+#define GEN3_EQ_FB_MODE_DIR_CHANGE_OFF 0x8ac
+#define GEN3_EQ_FMDC_T_MIN_PHASE23 GENMASK(4, 0)
+#define GEN3_EQ_FMDC_N_EVALS GENMASK(9, 5)
+#define GEN3_EQ_FMDC_MAX_PRE_CUSROR_DELTA GENMASK(13, 10)
+#define GEN3_EQ_FMDC_MAX_POST_CUSROR_DELTA GENMASK(17, 14)
+
#define PCIE_PORT_MULTI_LANE_CTRL 0x8C0
#define PORT_MLTI_UPCFG_SUPPORT BIT(7)
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..dc7d93db9dc5
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/pci.h>
+
+#include "pcie-designware.h"
+#include "pcie-qcom-common.h"
+
+void qcom_pcie_common_set_16gt_eq_settings(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_*. RATE_SHADOW_SEL bit field of GEN3_RELATED_OFF determines
+ * data rate for which this 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, 0x1);
+ 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_eq_settings);
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
new file mode 100644
index 000000000000..259e04b7bdf9
--- /dev/null
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include "pcie-designware.h"
+
+void qcom_pcie_common_set_16gt_eq_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 236229f66c80..af83470216e8 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -25,6 +25,7 @@
#include "../../pci.h"
#include "pcie-designware.h"
+#include "pcie-qcom-common.h"
/* PARF registers */
#define PARF_SYS_CTRL 0x00
@@ -486,6 +487,9 @@ 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)
+ qcom_pcie_common_set_16gt_eq_settings(pci);
+
/*
* The physical address of the MMIO region which is exposed as the BAR
* should be written to MHI BASE registers.
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 0180edf3310e..2742e82fdcb3 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -35,6 +35,7 @@
#include "../../pci.h"
#include "pcie-designware.h"
+#include "pcie-qcom-common.h"
/* PARF registers */
#define PARF_SYS_CTRL 0x00
@@ -283,6 +284,9 @@ 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)
+ qcom_pcie_common_set_16gt_eq_settings(pci);
+
/* Enable Link Training state machine */
if (pcie->cfg->ops->ltssm_enable)
pcie->cfg->ops->ltssm_enable(pcie);
--
2.25.1
