> -----Original Message-----
> From: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Sent: Wednesday, March 24, 2021 5:30 PM
> To: Richard Zhu <hongxing.zhu@xxxxxxx>; andrew.smirnov@xxxxxxxxx;
> shawnguo@xxxxxxxxxx; kw@xxxxxxxxx; bhelgaas@xxxxxxxxxx;
> stefan@xxxxxxxx; lorenzo.pieralisi@xxxxxxx
> Cc: linux-pci@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> kernel@xxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 3/3] PCI: imx: clear vreg bypass when pcie vph
> voltage is 3v3
> Am Mittwoch, dem 24.03.2021 um 13:34 +0800 schrieb Richard Zhu:
> > Both 1.8v and 3.3v power supplies can be used by i.MX8MQ PCIe PHY.
> > In default, the PCIE_VPH voltage is suggested to be 1.8v refer to data
> > sheet. When PCIE_VPH is supplied by 3.3v in the HW schematic design,
> > the VREG_BYPASS bits of GPR registers should be cleared from default
> > value 1b'1 to 1b'0. Thus, the internal 3v3 to 1v8 translator would be
> > turned on.
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pci-imx6.c | 23 +++++++++++++++++++++++
> > 1 file changed, 23 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 853ea8e82952..beca085a9300 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -37,6 +37,7 @@
> > #define IMX8MQ_GPR_PCIE_REF_USE_PAD BIT(9)
> > #define IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN BIT(10)
> > #define IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE BIT(11)
> > +#define IMX8MQ_GPR_PCIE_VREG_BYPASS BIT(12)
> > #define IMX8MQ_GPR12_PCIE2_CTRL_DEVICE_TYPE GENMASK(11, 8)
> > #define IMX8MQ_PCIE2_BASE_ADDR
> 0x33c00000
> >
> >
> >
> >
> > @@ -80,6 +81,7 @@ struct imx6_pcie {
> > u32 tx_swing_full;
> > u32 tx_swing_low;
> > struct regulator *vpcie;
> > + struct regulator *vph;
> > void __iomem *phy_base;
> >
> >
> >
> >
> > /* power domain for pcie */
> > @@ -611,6 +613,8 @@ static void imx6_pcie_configure_type(struct
> > imx6_pcie *imx6_pcie)
> >
> >
> >
> >
> > static void imx6_pcie_init_phy(struct imx6_pcie *imx6_pcie) {
> > + int phy_uv;
> > +
> No need for this variable...
[Richard Zhu] Thanks, would be removed later.
>
> > switch (imx6_pcie->drvdata->variant) {
> > case IMX8MQ:
> > /*
> > @@ -621,6 +625,18 @@ static void imx6_pcie_init_phy(struct imx6_pcie
> *imx6_pcie)
> > imx6_pcie_grp_offset(imx6_pcie),
> >
> IMX8MQ_GPR_PCIE_REF_USE_PAD,
> >
> IMX8MQ_GPR_PCIE_REF_USE_PAD);
> > + /*
> > + * Regarding to the datasheet, the PCIE_VPH is suggested
> > + * to be 1.8V. If the PCIE_VPH is supplied by 3.3V, the
> > + * VREG_BYPASS should be cleared to zero.
> > + */
> > + if (imx6_pcie->vph)
> > + phy_uv =
> regulator_get_voltage(imx6_pcie->vph);
> > + if (phy_uv > 3000000)
> > + regmap_update_bits(imx6_pcie->iomuxc_gpr,
> > +
> imx6_pcie_grp_offset(imx6_pcie),
> > +
> IMX8MQ_GPR_PCIE_VREG_BYPASS,
> > + 0);
>
> ...if you just fold this into a single condition. Right now phy_uv might be used
> uninitialized when the vph-supply is not specified in the DT. Better write this
> as:
>
> if (imx6_pcie->vph && regulator_get_voltage(imx6_pcie->vph) > 3000000)
[Richard Zhu] Thanks. Would be changed as this way.
>
> Regards,
> Lucas
>
> > break;
> > case IMX7D:
> > regmap_update_bits(imx6_pcie->iomuxc_gpr,
> IOMUXC_GPR12,
> > @@ -1130,6 +1146,13 @@ static int imx6_pcie_probe(struct
> platform_device *pdev)
> > imx6_pcie->vpcie = NULL;
> > }
> >
> >
> >
> >
> >
> >
> >
> >
> > + imx6_pcie->vph = devm_regulator_get_optional(&pdev->dev,
> "vph");
> > + if (IS_ERR(imx6_pcie->vph)) {
> > + if (PTR_ERR(imx6_pcie->vph) != -ENODEV)
> > + return PTR_ERR(imx6_pcie->vph);
> > + imx6_pcie->vph = NULL;
> > + }
> > +
> > platform_set_drvdata(pdev, imx6_pcie);
> >
> >
> >
> >
> >
> >
> >
> >
> > ret = imx6_pcie_attach_pd(dev);
>
