Add 16GT/s specific equalization and rx lane margining settings. These
settings are inline with respective PHY settings for 16GT/s
operation.
In addition, current QCOM EP and RC drivers do not share common
codebase which would result in code duplication. Hence, adding
common files for code reusability among RC and EP drivers.
v3 -> v4:
- Addressed review comments from Mani and Konrad.
- Preceded subject line with pci: qcom: tags
v2 -> v3:
- Replaced FIELD_GET/FIELD_PREP macros for bit operations.
- Renamed cmn to common.
- Avoided unnecessary argument validations.
- Addressed review comments from Konrad and Mani.
v1 -> v2:
- Capitilized commit message to be inline with history
- Dropped stubs from header file.
- Moved Designware specific register offsets and masks to
pcie-designware.h header file.
- Applied settings based on bus data rate rather than link generation.
- Addressed review comments from Bjorn and Frank.
Shashank Babu Chinta Venkata (3):
PCI: qcom: Refactor common code
PCI: qcom: Add equalization settings for 16 GT/s
PCI: qcom: Add RX margining settings for 16 GT/s
drivers/pci/controller/dwc/Kconfig | 5 +
drivers/pci/controller/dwc/Makefile | 1 +
drivers/pci/controller/dwc/pcie-designware.h | 30 ++++
drivers/pci/controller/dwc/pcie-qcom-common.c | 144 ++++++++++++++++++
drivers/pci/controller/dwc/pcie-qcom-common.h | 14 ++
drivers/pci/controller/dwc/pcie-qcom-ep.c | 44 ++----
drivers/pci/controller/dwc/pcie-qcom.c | 74 ++-------
7 files changed, 218 insertions(+), 94 deletions(-)
create mode 100644 drivers/pci/controller/dwc/pcie-qcom-common.c
create mode 100644 drivers/pci/controller/dwc/pcie-qcom-common.h
--
2.43.2
Add RX lane margining settings for 16 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 <[email protected]>
---
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 ed0045043847..343450c04e05 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -203,6 +203,24 @@
#define PCIE_PL_CHK_REG_ERR_ADDR 0xB28
+/*
+ * 16 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 16c277b2e9d4..fe6f7dde5d8c 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
@@ -53,6 +53,37 @@ void qcom_pcie_common_set_16gt_eq_settings(struct dw_pcie *pci)
}
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);
+
struct icc_path *qcom_pcie_common_icc_get_resource(struct dw_pcie *pci, const char *path)
{
struct icc_path *icc_mem_p;
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
index 5c01f6c18b3b..c7eb87aa0677 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.h
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
@@ -11,3 +11,4 @@ struct icc_path *qcom_pcie_common_icc_get_resource(struct dw_pcie *pci, const ch
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);
+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 7940222d35f6..2aea78da9c5b 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -438,8 +438,10 @@ 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)
+ if (pcie_link_speed[pci->link_gen] == 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 525942f2cf98..9b3d7729b34b 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -263,8 +263,10 @@ 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)
+ if (pcie_link_speed[pci->link_gen] == 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)
--
2.43.2
During high data transmission rates such as 16 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 equilization settings at both transmitter and receiver. This will
result in increasing PCIe signal strength.
Signed-off-by: Shashank Babu Chinta Venkata <[email protected]>
---
drivers/pci/controller/dwc/pcie-designware.h | 12 ++++++
drivers/pci/controller/dwc/pcie-qcom-common.c | 37 +++++++++++++++++++
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, 56 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 26dae4837462..ed0045043847 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 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
index 228d9eec0222..16c277b2e9d4 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
@@ -16,6 +16,43 @@
#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 register is repurposed to apply equilaztion
+ * 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 equilization 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);
+
struct icc_path *qcom_pcie_common_icc_get_resource(struct dw_pcie *pci, const char *path)
{
struct icc_path *icc_mem_p;
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
index da1760c7e164..5c01f6c18b3b 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.h
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
@@ -10,3 +10,4 @@
struct icc_path *qcom_pcie_common_icc_get_resource(struct dw_pcie *pci, const char *path);
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 f0c61d847643..7940222d35f6 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 0095c42aeee0..525942f2cf98 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