[v5] Add Equalization Settings for 8.0 GT/s and 32.0 GT/s and Add PCIe Lane Equalization Preset Properties for 8.0 GT/s and 16.0 GT/s

[PATCH v5 1/3] PCI: qcom: Add equalization settings for 8.0 GT/s and 32.0 GT/s

Posted by Ziyue Zhang 1 month, 2 weeks ago

Add lane equalization setting for 8.0 GT/s and 32.0 GT/s to enhance link
stability and avoid AER Correctable Errors reported on some platforms
(eg. SA8775P).

8.0 GT/s, 16.0 GT/s and 32.0 GT/s require the same equalization setting.
This setting is programmed into a group of shadow registers, which can be
switched to configure equalization for different speeds by writing 00b,
01b and 10b to `RATE_SHADOW_SEL`.

Hence program equalization registers in a loop using link speed as index,
so that equalization setting can be programmed for 8.0 GT/s, 16.0 GT/s
and 32.0 GT/s.

Co-developed-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
Signed-off-by: Ziyue Zhang <ziyue.zhang@oss.qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-designware.h  |  1 -
 drivers/pci/controller/dwc/pcie-qcom-common.c | 58 +++++++++++--------
 drivers/pci/controller/dwc/pcie-qcom-common.h |  2 +-
 drivers/pci/controller/dwc/pcie-qcom-ep.c     |  6 +-
 drivers/pci/controller/dwc/pcie-qcom.c        |  6 +-
 5 files changed, 41 insertions(+), 32 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index b5e7e18138a6..11de844428e5 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -123,7 +123,6 @@
 #define GEN3_RELATED_OFF_GEN3_EQ_DISABLE	BIT(16)
 #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_SHIFT	24
 #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK	GENMASK(25, 24)
-#define GEN3_RELATED_OFF_RATE_SHADOW_SEL_16_0GT	0x1
 
 #define GEN3_EQ_CONTROL_OFF			0x8A8
 #define GEN3_EQ_CONTROL_OFF_FB_MODE		GENMASK(3, 0)
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.c b/drivers/pci/controller/dwc/pcie-qcom-common.c
index 3aad19b56da8..cb98e66d81d9 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
@@ -8,9 +8,11 @@
 #include "pcie-designware.h"
 #include "pcie-qcom-common.h"
 
-void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci)
+void qcom_pcie_common_set_equalization(struct dw_pcie *pci)
 {
 	u32 reg;
+	u16 speed;
+	struct device *dev = pci->dev;
 
 	/*
 	 * GEN3_RELATED_OFF register is repurposed to apply equalization
@@ -19,32 +21,40 @@ void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci)
 	 * 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);
+	for (speed = PCIE_SPEED_8_0GT; speed <= pcie_link_speed[pci->max_link_speed]; ++speed) {
+		if (speed > PCIE_SPEED_32_0GT) {
+			dev_warn(dev, "Skipped equalization settings for speeds higher than 32.0 GT/s\n");
+			break;
+		}
 
-	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);
+		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,
+			  speed - PCIE_SPEED_8_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);
+EXPORT_SYMBOL_GPL(qcom_pcie_common_set_equalization);
 
 void qcom_pcie_common_set_16gt_lane_margining(struct dw_pcie *pci)
 {
diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
index 7d88d29e4766..7f5ca2fd9a72 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-common.h
+++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
@@ -8,7 +8,7 @@
 
 struct dw_pcie;
 
-void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci);
+void qcom_pcie_common_set_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 60afb4d0134c..aeb166f68d55 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -511,10 +511,10 @@ 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) {
-		qcom_pcie_common_set_16gt_equalization(pci);
+	qcom_pcie_common_set_equalization(pci);
+
+	if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT)
 		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 294babe1816e..31841ab9498b 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -322,10 +322,10 @@ 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) {
-		qcom_pcie_common_set_16gt_equalization(pci);
+	qcom_pcie_common_set_equalization(pci);
+
+	if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT)
 		qcom_pcie_common_set_16gt_lane_margining(pci);
-	}
 
 	/* Enable Link Training state machine */
 	if (pcie->cfg->ops->ltssm_enable)
-- 
2.43.0

Re: [PATCH v5 1/3] PCI: qcom: Add equalization settings for 8.0 GT/s and 32.0 GT/s

Posted by Manivannan Sadhasivam 1 month, 1 week ago

On Tue, Aug 19, 2025 at 03:16:46PM GMT, Ziyue Zhang wrote:
> Add lane equalization setting for 8.0 GT/s and 32.0 GT/s to enhance link
> stability and avoid AER Correctable Errors reported on some platforms
> (eg. SA8775P).
> 

So this is fixing an issue, right? Then you should add relevant Fixes tag. I
guess the tag here would be the commit that added SA8775p.

> 8.0 GT/s, 16.0 GT/s and 32.0 GT/s require the same equalization setting.
> This setting is programmed into a group of shadow registers, which can be
> switched to configure equalization for different speeds by writing 00b,
> 01b and 10b to `RATE_SHADOW_SEL`.
> 
> Hence program equalization registers in a loop using link speed as index,
> so that equalization setting can be programmed for 8.0 GT/s, 16.0 GT/s
> and 32.0 GT/s.
> 
> Co-developed-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
> Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
> Signed-off-by: Ziyue Zhang <ziyue.zhang@oss.qualcomm.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware.h  |  1 -
>  drivers/pci/controller/dwc/pcie-qcom-common.c | 58 +++++++++++--------
>  drivers/pci/controller/dwc/pcie-qcom-common.h |  2 +-
>  drivers/pci/controller/dwc/pcie-qcom-ep.c     |  6 +-
>  drivers/pci/controller/dwc/pcie-qcom.c        |  6 +-
>  5 files changed, 41 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index b5e7e18138a6..11de844428e5 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -123,7 +123,6 @@
>  #define GEN3_RELATED_OFF_GEN3_EQ_DISABLE	BIT(16)
>  #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_SHIFT	24
>  #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK	GENMASK(25, 24)
> -#define GEN3_RELATED_OFF_RATE_SHADOW_SEL_16_0GT	0x1
>  
>  #define GEN3_EQ_CONTROL_OFF			0x8A8
>  #define GEN3_EQ_CONTROL_OFF_FB_MODE		GENMASK(3, 0)
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.c b/drivers/pci/controller/dwc/pcie-qcom-common.c
> index 3aad19b56da8..cb98e66d81d9 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-common.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
> @@ -8,9 +8,11 @@
>  #include "pcie-designware.h"
>  #include "pcie-qcom-common.h"
>  
> -void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci)
> +void qcom_pcie_common_set_equalization(struct dw_pcie *pci)
>  {
>  	u32 reg;
> +	u16 speed;
> +	struct device *dev = pci->dev;

Reverse Xmas order please.

>  
>  	/*
>  	 * GEN3_RELATED_OFF register is repurposed to apply equalization
> @@ -19,32 +21,40 @@ void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci)
>  	 * 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);
> +	for (speed = PCIE_SPEED_8_0GT; speed <= pcie_link_speed[pci->max_link_speed]; ++speed) {
> +		if (speed > PCIE_SPEED_32_0GT) {
> +			dev_warn(dev, "Skipped equalization settings for speeds higher than 32.0 GT/s\n");
> +			break;
> +		}
>  
> -	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);
> +		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,
> +			  speed - PCIE_SPEED_8_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);
> +EXPORT_SYMBOL_GPL(qcom_pcie_common_set_equalization);
>  
>  void qcom_pcie_common_set_16gt_lane_margining(struct dw_pcie *pci)
>  {
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
> index 7d88d29e4766..7f5ca2fd9a72 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-common.h
> +++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
> @@ -8,7 +8,7 @@
>  
>  struct dw_pcie;
>  
> -void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci);
> +void qcom_pcie_common_set_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 60afb4d0134c..aeb166f68d55 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> @@ -511,10 +511,10 @@ 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) {
> -		qcom_pcie_common_set_16gt_equalization(pci);
> +	qcom_pcie_common_set_equalization(pci);
> +
> +	if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT)

This condition has existed even before this patch, but just noticing this
possible issue. So if 'max_link_speed' is > 16 GT/s, we do not need to set lane
margining? We used the same logic to set equalization setting earlier also.

- Mani

-- 
மணிவண்ணன் சதாசிவம்

Re: [PATCH v5 1/3] PCI: qcom: Add equalization settings for 8.0 GT/s and 32.0 GT/s

Posted by Qiang Yu 1 month, 1 week ago


On 8/22/2025 4:06 PM, Manivannan Sadhasivam wrote:
> On Tue, Aug 19, 2025 at 03:16:46PM GMT, Ziyue Zhang wrote:
>> Add lane equalization setting for 8.0 GT/s and 32.0 GT/s to enhance link
>> stability and avoid AER Correctable Errors reported on some platforms
>> (eg. SA8775P).
>>
> 
> So this is fixing an issue, right? Then you should add relevant Fixes tag. I
> guess the tag here would be the commit that added SA8775p.
> 
>> 8.0 GT/s, 16.0 GT/s and 32.0 GT/s require the same equalization setting.
>> This setting is programmed into a group of shadow registers, which can be
>> switched to configure equalization for different speeds by writing 00b,
>> 01b and 10b to `RATE_SHADOW_SEL`.
>>
>> Hence program equalization registers in a loop using link speed as index,
>> so that equalization setting can be programmed for 8.0 GT/s, 16.0 GT/s
>> and 32.0 GT/s.
>>
>> Co-developed-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
>> Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
>> Signed-off-by: Ziyue Zhang <ziyue.zhang@oss.qualcomm.com>
>> ---
>>   drivers/pci/controller/dwc/pcie-designware.h  |  1 -
>>   drivers/pci/controller/dwc/pcie-qcom-common.c | 58 +++++++++++--------
>>   drivers/pci/controller/dwc/pcie-qcom-common.h |  2 +-
>>   drivers/pci/controller/dwc/pcie-qcom-ep.c     |  6 +-
>>   drivers/pci/controller/dwc/pcie-qcom.c        |  6 +-
>>   5 files changed, 41 insertions(+), 32 deletions(-)
>>
>> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
>> index b5e7e18138a6..11de844428e5 100644
>> --- a/drivers/pci/controller/dwc/pcie-designware.h
>> +++ b/drivers/pci/controller/dwc/pcie-designware.h
>> @@ -123,7 +123,6 @@
>>   #define GEN3_RELATED_OFF_GEN3_EQ_DISABLE	BIT(16)
>>   #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_SHIFT	24
>>   #define GEN3_RELATED_OFF_RATE_SHADOW_SEL_MASK	GENMASK(25, 24)
>> -#define GEN3_RELATED_OFF_RATE_SHADOW_SEL_16_0GT	0x1
>>   
>>   #define GEN3_EQ_CONTROL_OFF			0x8A8
>>   #define GEN3_EQ_CONTROL_OFF_FB_MODE		GENMASK(3, 0)
>> diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.c b/drivers/pci/controller/dwc/pcie-qcom-common.c
>> index 3aad19b56da8..cb98e66d81d9 100644
>> --- a/drivers/pci/controller/dwc/pcie-qcom-common.c
>> +++ b/drivers/pci/controller/dwc/pcie-qcom-common.c
>> @@ -8,9 +8,11 @@
>>   #include "pcie-designware.h"
>>   #include "pcie-qcom-common.h"
>>   
>> -void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci)
>> +void qcom_pcie_common_set_equalization(struct dw_pcie *pci)
>>   {
>>   	u32 reg;
>> +	u16 speed;
>> +	struct device *dev = pci->dev;
> 
> Reverse Xmas order please.
> 
>>   
>>   	/*
>>   	 * GEN3_RELATED_OFF register is repurposed to apply equalization
>> @@ -19,32 +21,40 @@ void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci)
>>   	 * 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);
>> +	for (speed = PCIE_SPEED_8_0GT; speed <= pcie_link_speed[pci->max_link_speed]; ++speed) {
>> +		if (speed > PCIE_SPEED_32_0GT) {
>> +			dev_warn(dev, "Skipped equalization settings for speeds higher than 32.0 GT/s\n");
>> +			break;
>> +		}
>>   
>> -	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);
>> +		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,
>> +			  speed - PCIE_SPEED_8_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);
>> +EXPORT_SYMBOL_GPL(qcom_pcie_common_set_equalization);
>>   
>>   void qcom_pcie_common_set_16gt_lane_margining(struct dw_pcie *pci)
>>   {
>> diff --git a/drivers/pci/controller/dwc/pcie-qcom-common.h b/drivers/pci/controller/dwc/pcie-qcom-common.h
>> index 7d88d29e4766..7f5ca2fd9a72 100644
>> --- a/drivers/pci/controller/dwc/pcie-qcom-common.h
>> +++ b/drivers/pci/controller/dwc/pcie-qcom-common.h
>> @@ -8,7 +8,7 @@
>>   
>>   struct dw_pcie;
>>   
>> -void qcom_pcie_common_set_16gt_equalization(struct dw_pcie *pci);
>> +void qcom_pcie_common_set_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 60afb4d0134c..aeb166f68d55 100644
>> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
>> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
>> @@ -511,10 +511,10 @@ 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) {
>> -		qcom_pcie_common_set_16gt_equalization(pci);
>> +	qcom_pcie_common_set_equalization(pci);
>> +
>> +	if (pcie_link_speed[pci->max_link_speed] == PCIE_SPEED_16_0GT)
> 
> This condition has existed even before this patch, but just noticing this
> possible issue. So if 'max_link_speed' is > 16 GT/s, we do not need to set lane
> margining? We used the same logic to set equalization setting earlier also.

Lane margining is supported for 16 GT/s and 32 GT/s. The settings are
dependent on phy design. For a specific phy, they have same settings
for 16 GT/s and 32 GT/s. Perhaps we can get the settings from devicetree
and program them in a loop.

But I'm not sure why we need to program it. It will no affect singal
quality and only required when user wants to collect margining info.

- Qiang Yu

> 
> - Mani
>

[PATCH v5 1/3] PCI: qcom: Add equalization settings for 8.0 GT/s and 32.0 GT/s
[PATCH v5 2/3] PCI: qcom: fix macro typo for CURSOR
[PATCH v5 3/3] arm64: dts: qcom: lemans: Add PCIe lane equalization preset properties