[PATCH v3 2/3] PCI: qcom: Add equalization settings for 16GT/s
From: Shashank Babu Chinta Venkata
Date: Thu Apr 18 2024 - 20:12:54 EST
GEN3_RELATED_OFFSET is being used to determine data rate of shadow
registers. Select data rate as 16GT/s and set appropriate equilization
settings to improve link stability for 16GT/s data rate.
Signed-off-by: Shashank Babu Chinta Venkata <quic_schintav@xxxxxxxxxxx>
---
drivers/pci/controller/dwc/pcie-designware.h | 12 ++++++++
drivers/pci/controller/dwc/pcie-qcom-common.c | 30 +++++++++++++++++++
drivers/pci/controller/dwc/pcie-qcom-common.h | 1 +
drivers/pci/controller/dwc/pcie-qcom-ep.c | 3 ++
drivers/pci/controller/dwc/pcie-qcom.c | 3 ++
5 files changed, 49 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 26dae4837462..ad771bb52d29 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -122,6 +122,18 @@
#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(n) FIELD_PREP(GENMASK(3, 0), n)
+#define GEN3_EQ_CONTROL_OFF_PHASE23_EXIT_MODE(n) FIELD_PREP(BIT(4), n)
+#define GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC(n) FIELD_PREP(GENMASK(23, 8), n)
+#define GEN3_EQ_CONTROL_OFF_FOM_INC_INITIAL_EVAL(n) FIELD_PREP(BIT(24), n)
+
+#define GEN3_EQ_FB_MODE_DIR_CHANGE_OFF 0x8ac
+#define GEN3_EQ_FMDC_T_MIN_PHASE23(n) FIELD_PREP(GENMASK(4, 0), n)
+#define GEN3_EQ_FMDC_N_EVALS(n) FIELD_PREP(GENMASK(9, 5), n)
+#define GEN3_EQ_FMDC_MAX_PRE_CUSROR_DELTA(n) FIELD_PREP(GENMASK(13, 10), n)
+#define GEN3_EQ_FMDC_MAX_POST_CUSROR_DELTA(n) FIELD_PREP(GENMASK(17, 14), n)
+
#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
index dc2120ec5fef..a6f3eb4c3ee6 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
@@ -16,6 +16,36 @@
#define QCOM_PCIE_LINK_SPEED_TO_BW(speed) \
Mbps_to_icc(PCIE_SPEED2MBS_ENC(pcie_link_speed[speed]))
+void qcom_pcie_common_set_16gt_eq_settings(struct dw_pcie *pci)
+{
+ u32 reg;
+
+ /*
+ * GEN3_RELATED_OFF is repurposed to be used with GEN4(16GT/s) rate
+ * as well based on RATE_SHADOW_SEL_MASK settings on this register.
+ */
+ 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 |= (0x1 << GEN3_RELATED_OFF_RATE_SHADOW_SEL_SHIFT);
+ 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(0) |
+ GEN3_EQ_FMDC_N_EVALS(0xD) |
+ GEN3_EQ_FMDC_MAX_PRE_CUSROR_DELTA(0x5) |
+ 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(0) |
+ GEN3_EQ_CONTROL_OFF_PHASE23_EXIT_MODE(0) |
+ GEN3_EQ_CONTROL_OFF_FOM_INC_INITIAL_EVAL(0) |
+ GEN3_EQ_CONTROL_OFF_PSET_REQ_VEC(0);
+ dw_pcie_writel_dbi(pci, GEN3_EQ_CONTROL_OFF, reg);
+}
+EXPORT_SYMBOL_GPL(qcom_pcie_common_set_16gt_eq_settings);
+
int qcom_pcie_common_icc_get_resource(struct dw_pcie *pci, struct icc_path **icc_mem_p)
{
*icc_mem_p = devm_of_icc_get(pci->dev, "pcie-mem");
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
index f0520d7301da..e72c651b0d28 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.h
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
@@ -10,3 +10,4 @@
int qcom_pcie_common_icc_get_resource(struct dw_pcie *pci, struct icc_path **icc_mem_p);
int qcom_pcie_common_icc_init(struct dw_pcie *pci, struct icc_path *icc_mem);
void qcom_pcie_common_icc_update(struct dw_pcie *pci, struct icc_path *icc_mem);
+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 11c99b358147..cb75a874f76c 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -438,6 +438,9 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
goto err_disable_resources;
}
+ if (pcie_link_speed[pci->link_gen] == 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 71f011daad1d..acf66f974edc 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -263,6 +263,9 @@ static int qcom_pcie_start_link(struct dw_pcie *pci)
{
struct qcom_pcie *pcie = to_qcom_pcie(pci);
+ if (pcie_link_speed[pci->link_gen] == 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);
--
2.43.2