Re: [PATCH v2] PCI: imx6: Add DT bindings to configure Tx Driver settings

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Feb 19, 2016 at 03:25:26PM -0500, Justin Waters wrote:
> On Thu, Feb 4, 2016 at 12:25 PM, Bjorn Helgaas <helgaas@kernel.org> wrote:
> > [+cc Richard]
> >
> > On Fri, Jan 15, 2016 at 10:24:35AM -0500, Justin Waters wrote:
> >> The settings in GPR8 are dependent upon the particular layout of the
> >> hardware platform. As such, they should be configurable via the device
> >> tree.
> >>
> >> As many boards have been using the default values, this implementation
> >> uses the old values if they are not specified in the device tree.
> >>
> >> Signed-off-by: Justin Waters <justin.waters@timesys.com>
> >
> > Waiting for an ack from Lucas, since he had comments on the last version.
> >
> 
> Lucas, I just wanted to check in and see if you had any additional
> feedback for me. Did v2 address your concerns?

Just to be clear, I'm waiting for an ack from the IMX6 maintainers
(Richard or Lucas) before applying this.

> >> ---
> >>  .../devicetree/bindings/pci/fsl,imx6q-pcie.txt     |  7 ++++
> >>  drivers/pci/host/pci-imx6.c                        | 42 +++++++++++++++++++---
> >>  2 files changed, 44 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> >> index 6fbba53..3be80c6 100644
> >> --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> >> +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> >> @@ -13,6 +13,13 @@ Required properties:
> >>  - clock-names: Must include the following additional entries:
> >>       - "pcie_phy"
> >>
> >> +Optional properties:
> >> +- fsl,tx-deemph-gen1: Gen1 De-emphasis value. Default: 0
> >> +- fsl,tx-deemph-gen2-3p5db: Gen2 (3.5db) De-emphasis value. Default: 0
> >> +- fsl,tx-deemph-gen2-6db: Gen2 (6db) De-emphasis value. Default: 20
> >> +- fsl,tx-swing-full: Gen2 TX SWING FULL value. Default: 127
> >> +- fsl,tx-swing-low: TX launch amplitude swing_low value. Default: 127
> >> +
> >>  Example:
> >>
> >>       pcie@0x01000000 {
> >> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> >> index 230ebf9..cc04497 100644
> >> --- a/drivers/pci/host/pci-imx6.c
> >> +++ b/drivers/pci/host/pci-imx6.c
> >> @@ -39,6 +39,11 @@ struct imx6_pcie {
> >>       struct pcie_port        pp;
> >>       struct regmap           *iomuxc_gpr;
> >>       void __iomem            *mem_base;
> >> +     u32                     tx_deemph_gen1;
> >> +     u32                     tx_deemph_gen2_3p5db;
> >> +     u32                     tx_deemph_gen2_6db;
> >> +     u32                     tx_swing_full;
> >> +     u32                     tx_swing_low;
> >>  };
> >>
> >>  /* PCIe Root Complex registers (memory-mapped) */
> >> @@ -317,15 +322,20 @@ static void imx6_pcie_init_phy(struct pcie_port *pp)
> >>                       IMX6Q_GPR12_LOS_LEVEL, 9 << 4);
> >>
> >>       regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
> >> -                     IMX6Q_GPR8_TX_DEEMPH_GEN1, 0 << 0);
> >> +                        IMX6Q_GPR8_TX_DEEMPH_GEN1,
> >> +                        imx6_pcie->tx_deemph_gen1 << 0);
> >>       regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
> >> -                     IMX6Q_GPR8_TX_DEEMPH_GEN2_3P5DB, 0 << 6);
> >> +                        IMX6Q_GPR8_TX_DEEMPH_GEN2_3P5DB,
> >> +                        imx6_pcie->tx_deemph_gen2_3p5db << 6);
> >>       regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
> >> -                     IMX6Q_GPR8_TX_DEEMPH_GEN2_6DB, 20 << 12);
> >> +                        IMX6Q_GPR8_TX_DEEMPH_GEN2_6DB,
> >> +                        imx6_pcie->tx_deemph_gen2_6db << 12);
> >>       regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
> >> -                     IMX6Q_GPR8_TX_SWING_FULL, 127 << 18);
> >> +                        IMX6Q_GPR8_TX_SWING_FULL,
> >> +                        imx6_pcie->tx_swing_full << 18);
> >>       regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
> >> -                     IMX6Q_GPR8_TX_SWING_LOW, 127 << 25);
> >> +                        IMX6Q_GPR8_TX_SWING_LOW,
> >> +                        imx6_pcie->tx_swing_low << 25);
> >>  }
> >>
> >>  static int imx6_pcie_wait_for_link(struct pcie_port *pp)
> >> @@ -565,6 +575,7 @@ static int __init imx6_pcie_probe(struct platform_device *pdev)
> >>       struct imx6_pcie *imx6_pcie;
> >>       struct pcie_port *pp;
> >>       struct resource *dbi_base;
> >> +     struct device_node *node = pdev->dev.of_node;
> >>       int ret;
> >>
> >>       imx6_pcie = devm_kzalloc(&pdev->dev, sizeof(*imx6_pcie), GFP_KERNEL);
> >> @@ -617,6 +628,27 @@ static int __init imx6_pcie_probe(struct platform_device *pdev)
> >>               return PTR_ERR(imx6_pcie->iomuxc_gpr);
> >>       }
> >>
> >> +     /* Grab PCIe PHY Tx Settings */
> >> +     if (of_property_read_u32
> >> +         (node, "fsl,tx-deemph-gen1", &imx6_pcie->tx_deemph_gen1))
> >> +             imx6_pcie->tx_deemph_gen1 = 0;
> >> +
> >> +     if (of_property_read_u32
> >> +         (node, "fsl,tx-deemph-gen2-3p5db", &imx6_pcie->tx_deemph_gen2_3p5db))
> >> +             imx6_pcie->tx_deemph_gen2_3p5db = 0;
> >> +
> >> +     if (of_property_read_u32
> >> +         (node, "fsl,tx-deemph-gen2-6db", &imx6_pcie->tx_deemph_gen2_6db))
> >> +             imx6_pcie->tx_deemph_gen2_6db = 20;
> >> +
> >> +     if (of_property_read_u32
> >> +         (node, "fsl,tx-swing-full", &imx6_pcie->tx_swing_full))
> >> +             imx6_pcie->tx_swing_full = 127;
> >> +
> >> +     if (of_property_read_u32
> >> +         (node, "fsl,tx-swing-low", &imx6_pcie->tx_swing_low))
> >> +             imx6_pcie->tx_swing_low = 127;
> >> +
> >>       ret = imx6_add_pcie_port(pp, pdev);
> >>       if (ret < 0)
> >>               return ret;
> >> --
> >> 2.5.0
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html