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    Subject[PATCH v3 7/8] phy: miphy28lp: Tune tx impedance across Soc cuts
    Date
    This patch to compensate tx impedance (Sata, PCIe)
    depending on Soc cuts the kernel is built for.

    Signed-off-by: Giuseppe Condorelli <giuseppe.condorelli@st.com>
    Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org>
    ---
    Documentation/devicetree/bindings/phy/phy-miphy28lp.txt | 1 +
    drivers/phy/phy-miphy28lp.c | 16 ++++++++++++++++
    2 files changed, 17 insertions(+)

    diff --git a/Documentation/devicetree/bindings/phy/phy-miphy28lp.txt b/Documentation/devicetree/bindings/phy/phy-miphy28lp.txt
    index daa8310..17f7eec 100644
    --- a/Documentation/devicetree/bindings/phy/phy-miphy28lp.txt
    +++ b/Documentation/devicetree/bindings/phy/phy-miphy28lp.txt
    @@ -40,6 +40,7 @@ Optional properties (port (child) node):
    - st,px_rx_pol_inv : to invert polarity of RXn/RXp (respectively negative line and positive
    line).
    - st,scc-on : enable ssc to reduce effects of EMI (only for sata or PCIe).
    +- st,tx-impedance-comp : to compensate tx impedance avoiding out of range values.

    example:

    diff --git a/drivers/phy/phy-miphy28lp.c b/drivers/phy/phy-miphy28lp.c
    index b6574e8..ac3fdf9 100644
    --- a/drivers/phy/phy-miphy28lp.c
    +++ b/drivers/phy/phy-miphy28lp.c
    @@ -201,6 +201,7 @@ struct miphy28lp_phy {
    bool osc_rdy;
    bool px_rx_pol_inv;
    bool ssc;
    + bool tx_impedance;

    struct reset_control *miphy_rst;

    @@ -608,6 +609,12 @@ static void miphy_pcie_tune_ssc(struct miphy28lp_phy *miphy_phy)
    }
    }

    +static inline void miphy_tune_tx_impedance(struct miphy28lp_phy *miphy_phy)
    +{
    + /* Compensate Tx impedance to avoid out of range values */
    + writeb_relaxed(0x02, miphy_phy->base + MIPHY_COMP_POSTP);
    +}
    +
    static inline int miphy28lp_configure_sata(struct miphy28lp_phy *miphy_phy)
    {
    void __iomem *base = miphy_phy->base;
    @@ -646,6 +653,9 @@ static inline int miphy28lp_configure_sata(struct miphy28lp_phy *miphy_phy)
    if (miphy_phy->ssc)
    miphy_sata_tune_ssc(miphy_phy);

    + if (miphy_phy->tx_impedance)
    + miphy_tune_tx_impedance(miphy_phy);
    +
    return 0;
    }

    @@ -679,6 +689,9 @@ static inline int miphy28lp_configure_pcie(struct miphy28lp_phy *miphy_phy)
    if (miphy_phy->ssc)
    miphy_pcie_tune_ssc(miphy_phy);

    + if (miphy_phy->tx_impedance)
    + miphy_tune_tx_impedance(miphy_phy);
    +
    return 0;
    }

    @@ -1117,6 +1130,9 @@ static int miphy28lp_of_probe(struct device_node *np,

    miphy_phy->ssc = of_property_read_bool(np, "st,ssc-on");

    + miphy_phy->tx_impedance =
    + of_property_read_bool(np, "st,tx-impedance-comp");
    +
    of_property_read_u32(np, "st,sata-gen", &miphy_phy->sata_gen);
    if (!miphy_phy->sata_gen)
    miphy_phy->sata_gen = SATA_GEN1;
    --
    1.9.1


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