linux-kernel - Re: [v2 2/3] drm/msm/dsi: Add dsi phy tuning configuration support

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Date:   Mon, 10 Jan 2022 17:12:17 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Rajeev Nandan <quic_rajeevny@...cinc.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, sean@...rly.run, robdclark@...il.com,
        robh+dt@...nel.org, robh@...nel.org, quic_abhinavk@...cinc.com,
        quic_kalyant@...cinc.com, quic_mkrishn@...cinc.com,
        jonathan@...ek.ca, airlied@...ux.ie, daniel@...ll.ch,
        swboyd@...omium.org
Subject: Re: [v2 2/3] drm/msm/dsi: Add dsi phy tuning configuration support

On Mon, 10 Jan 2022 at 15:56, Rajeev Nandan <quic_rajeevny@...cinc.com> wrote:
>
> Add support for MSM DSI PHY tuning configuration. Current design is
> to support drive strength and drive level/amplitude tuning for
> 10nm PHY version, but this can be extended to other PHY versions.
>
> Signed-off-by: Rajeev Nandan <quic_rajeevny@...cinc.com>
> ---
>
> Changes in v2:
>  - New.
>  - Split into generic code and 10nm-specific part (Dmitry Baryshkov)
>
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy.c |  3 +++
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy.h | 16 ++++++++++++++++
>  2 files changed, 19 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c
> index 8c65ef6..ee3739d 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.c
> @@ -739,6 +739,9 @@ static int dsi_phy_driver_probe(struct platform_device *pdev)
>                 }
>         }
>
> +       if (phy->cfg->ops.tuning_cfg_init)
> +               phy->cfg->ops.tuning_cfg_init(phy);

Please rename to parse_dt_properties() or something like that.

> +
>         ret = dsi_phy_regulator_init(phy);
>         if (ret)
>                 goto fail;
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h
> index b91303a..b559a2b 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy.h
> @@ -25,6 +25,7 @@ struct msm_dsi_phy_ops {
>         void (*save_pll_state)(struct msm_dsi_phy *phy);
>         int (*restore_pll_state)(struct msm_dsi_phy *phy);
>         bool (*set_continuous_clock)(struct msm_dsi_phy *phy, bool enable);
> +       void (*tuning_cfg_init)(struct msm_dsi_phy *phy);
>  };
>
>  struct msm_dsi_phy_cfg {
> @@ -81,6 +82,20 @@ struct msm_dsi_dphy_timing {
>  #define DSI_PIXEL_PLL_CLK              1
>  #define NUM_PROVIDED_CLKS              2
>
> +#define DSI_LANE_MAX                   5
> +
> +/**
> + * struct msm_dsi_phy_tuning_cfg - Holds PHY tuning config parameters.
> + * @rescode_offset_top: Offset for pull-up legs rescode.
> + * @rescode_offset_bot: Offset for pull-down legs rescode.
> + * @vreg_ctrl: vreg ctrl to drive LDO level
> + */
> +struct msm_dsi_phy_tuning_cfg {
> +       u8 rescode_offset_top[DSI_LANE_MAX];
> +       u8 rescode_offset_bot[DSI_LANE_MAX];
> +       u8 vreg_ctrl;
> +};

How generic is this? In other words, you are adding a struct with the
generic name to the generic structure. I'd expect that it would be
common to several PHY generations.

> +
>  struct msm_dsi_phy {
>         struct platform_device *pdev;
>         void __iomem *base;
> @@ -98,6 +113,7 @@ struct msm_dsi_phy {
>
>         struct msm_dsi_dphy_timing timing;
>         const struct msm_dsi_phy_cfg *cfg;
> +       struct msm_dsi_phy_tuning_cfg tuning_cfg;
>
>         enum msm_dsi_phy_usecase usecase;
>         bool regulator_ldo_mode;
> --
> 2.7.4
>


-- 
With best wishes
Dmitry