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@xxxxxxxxxxxxxxxx>
> Signed-off-by: Qiang Yu <qiang.yu@xxxxxxxxxxxxxxxx>
> Signed-off-by: Ziyue Zhang <ziyue.zhang@xxxxxxxxxxxxxxxx>
> ---
> 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
--
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