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The margins worsened across > > voltage and temperature (VT) variations and different test matrices, > > potentially causing link stability issues. > > > > Testing with MPLLB_BANDWIDTH value of 140 (0x8c) shows significant > > improvement in bandwidth margins across all VT conditions and test > > scenarios. > > > > Implement PHY register write helper function and configure: > > - MPLLB_BW_OVRD_IN = 140 (0x8c) for improved bandwidth margin > > - MPLLB_BW_OVRD_EN to enable the override > > > > This ensures robust PCIe Gen3 performance across all operating > > conditions. > > > > Signed-off-by: Richard Zhu > > Reviewed-by: Frank Li > > --- > > Changes in v5: > > Update the commit log refer to Bjorn's suggestions. > > > > Changes in v4: > > Move the delay to imx95_pcie_init_phy() with a comment added. > > > > Changes in v3: > > Regarding Frank's comments, refine naming consistency and clarity. > > > > Changes in v2: > > Update the register name and bit definitions. > > Don't move IMX95_PCIE_PHY_CR_PARA_SEL settings. > > --- > > drivers/pci/controller/dwc/pci-imx6.c | 32 +++++++++++++++++++++++++++ > > 1 file changed, 32 insertions(+) > > > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c > > index 39790e66b98dc..3bc52c4781903 100644 > > --- a/drivers/pci/controller/dwc/pci-imx6.c > > +++ b/drivers/pci/controller/dwc/pci-imx6.c > > @@ -80,6 +80,17 @@ > > #define IMX95_SID_MASK GENMASK(5, 0) > > #define IMX95_MAX_LUT 32 > > > > +#define IMX95_PCIE_PHY_REG_ADDR 0x3008 > > +#define IMX95_PCIE_PHY_REG_EN BIT(31) > > +#define IMX95_PCIE_PHY_REG_ADDR_MASK GENMASK(15, 0) > > +#define IMX95_PCIE_PHY_REG_DATA 0x300c > > +#define IMX95_PCIE_PHY_MPLLB_OVRD_IN 0x2004 > > +/* BIT(10): Override enable for mpllb_bandwidth[15:0] */ > > +#define IMX95_PCIE_PHY_MPLLB_OVRD_BW_EN BIT(10) > > +/* Register offset: Override value for mpllb_bandwidth[15:0] */ > > +#define IMX95_PCIE_PHY_MPLLB_BW_IN 0x2005 > > +#define IMX95_PCIE_PHY_MPLLB_BW_VAL 0x8c > > + > > #define IMX95_PCIE_RST_CTRL 0x3010 > > #define IMX95_PCIE_COLD_RST BIT(0) > > > > @@ -270,6 +281,15 @@ static int imx95_pcie_select_ref_clk_src(struct imx_pcie *imx_pcie) > > return 0; > > } > > > > +static void imx95_pcie_phy_write(struct imx_pcie *imx_pcie, int addr, u16 data) > > +{ > > + regmap_update_bits(imx_pcie->iomuxc_gpr, IMX95_PCIE_PHY_REG_ADDR, > > + IMX95_PCIE_PHY_REG_EN, IMX95_PCIE_PHY_REG_EN); > > + regmap_update_bits(imx_pcie->iomuxc_gpr, IMX95_PCIE_PHY_REG_ADDR, > > + IMX95_PCIE_PHY_REG_ADDR_MASK, addr); > > + regmap_write(imx_pcie->iomuxc_gpr, IMX95_PCIE_PHY_REG_DATA, data); > > +} > > + > > static int imx95_pcie_init_phy(struct imx_pcie *imx_pcie) > > { > > /* > > @@ -290,6 +310,18 @@ static int imx95_pcie_init_phy(struct imx_pcie *imx_pcie) > > IMX95_PCIE_PHY_CR_PARA_SEL, > > IMX95_PCIE_PHY_CR_PARA_SEL); > > > > I've added regmap_read() to flush the IMX95_PCIE_PHY_CR_PARA_SEL update before > below delay, while applying. Thanks Frank > > - Mani > > -- > மணிவண்ணன் சதாசிவம் >