linux-kernel - Re: [PATCH v2 2/2] phy: qcom: Introduce new eDP PHY driver

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Date:   Sat, 16 Oct 2021 18:09:32 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>, linux-phy@...ts.infradead.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Abhinav Kumar <abhinavk@...eaurora.org>,
        Stephen Boyd <sboyd@...nel.org>
Subject: Re: [PATCH v2 2/2] phy: qcom: Introduce new eDP PHY driver

On Sat 16 Oct 11:36 CDT 2021, Dmitry Baryshkov wrote:

> On Sat, 16 Oct 2021 at 01:11, Bjorn Andersson
> <bjorn.andersson@...aro.org> wrote:
[..]
> > diff --git a/drivers/phy/qualcomm/phy-qcom-edp.c b/drivers/phy/qualcomm/phy-qcom-edp.c
[..]
> > +#define QSERDES_COM_SSC_EN_CENTER               0x0010
> > +#define QSERDES_COM_SSC_ADJ_PER1                0x0014
> > +#define QSERDES_COM_SSC_PER1                    0x001c
> > +#define QSERDES_COM_SSC_PER2                    0x0020
> > +#define QSERDES_COM_SSC_STEP_SIZE1_MODE0        0x0024
> > +#define QSERDES_COM_SSC_STEP_SIZE2_MODE0        0x0028
> 
> I think we might want to use register definitions from phy-qcom-qmp.h,
> so that it would be obvious, which generations are handled by the
> driver.
> 

I reviewed the all the registers and concluded that the QSERDES is V4,
so I included phy-qcom-qmp.h and used the SERDES_V4 defines instead.

The registers found in the PHY and LANE_TX blocks are specific to this
PHY, so I'm keeping these here.

[..]
> > +/*
> > + * Display Port PLL driver block diagram for branch clocks
> 
> Embedded DisplayPort
> 

Sounds good, I also updated the drawing below where suitable.

> > + *
> > + *              +------------------------------+
> > + *              |         DP_VCO_CLK           |
> > + *              |                              |
> > + *              |    +-------------------+     |
> > + *              |    |   (DP PLL/VCO)    |     |
> > + *              |    +---------+---------+     |
> > + *              |              v               |
> > + *              |   +----------+-----------+   |
[..]
> > +static struct clk_hw *
> > +qcom_edp_dp_clks_hw_get(struct of_phandle_args *clkspec, void *data)
> > +{
> > +       unsigned int idx = clkspec->args[0];
> > +       struct qcom_edp *edp = data;
> > +
> > +       if (idx >= 2) {
> > +               pr_err("%s: invalid index %u\n", __func__, idx);
> > +               return ERR_PTR(-EINVAL);
> > +       }
> > +
> > +       if (idx == 0)
> > +               return &edp->dp_link_hw;
> > +
> > +       return &edp->dp_pixel_hw;
> > +}
> 
> You might want to use of_clk_hw_onecell_get() instead of the special function.
> 

Yeah, that looks slightly cleaner.

> > +
> > +static int qcom_edp_clks_register(struct qcom_edp *edp, struct device_node *np)
> > +{
> > +       struct clk_init_data init = { };
> > +       int ret;
> > +
> > +       init.ops = &qcom_edp_dp_link_clk_ops;
> > +       init.name = "edp_phy_pll_link_clk";
> > +       edp->dp_link_hw.init = &init;
> > +       ret = devm_clk_hw_register(edp->dev, &edp->dp_link_hw);
> > +       if (ret)
> > +               return ret;
> > +
> > +       init.ops = &qcom_edp_dp_pixel_clk_ops;
> > +       init.name = "edp_phy_pll_vco_div_clk";
> > +       edp->dp_pixel_hw.init = &init;
> > +       ret = devm_clk_hw_register(edp->dev, &edp->dp_pixel_hw);
> > +       if (ret)
> > +               return ret;
> > +
> > +       return devm_of_clk_add_hw_provider(edp->dev, qcom_edp_dp_clks_hw_get, edp);
> > +}
[..]
> > +static struct platform_driver qcom_edp_phy_driver = {
> > +       .probe          = qcom_edp_phy_probe,
> > +       .driver = {
> > +               .name   = "qcom-edp-phy",
> > +               .of_match_table = qcom_edp_phy_match_table,
> > +       },
> > +};
> > +
> > +module_platform_driver(qcom_edp_phy_driver);
> > +
> > +MODULE_DESCRIPTION("Qualcomm eDP PHY driver");
> 
> Should we mention that it's a eDP QMP PHY driver in contrast to the
> old eDP from 8x74/8x84?
> 

Sure.

> Also MODULE_AUTHOR seems to be missing.
> 

Okay, I can add one of those.

Thanks,
Bjorn

> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.29.2
> >
> 
> 
> -- 
> With best wishes
> Dmitry