linux-kernel - Re: [PATCH RESEND v3 3/5] clk: qcom: gdsc: Add set and get hwmode callbacks to switch GDSC mode

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Message-ID: <CAA8EJpqTafxkXfAZXdTCat1VphvHUTTWe1TUjbpMvqta1Jf+Cw@mail.gmail.com>
Date:   Wed, 1 Nov 2023 23:28:52 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Abel Vesa <abel.vesa@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Stanimir Varbanov <stanimir.k.varbanov@...il.com>,
        Vikash Garodia <quic_vgarodia@...cinc.com>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Taniya Das <tdas@....qualcomm.com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-media@...r.kernel.org,
        Jagadeesh Kona <quic_jkona@...cinc.com>
Subject: Re: [PATCH RESEND v3 3/5] clk: qcom: gdsc: Add set and get hwmode
 callbacks to switch GDSC mode

On Wed, 1 Nov 2023 at 11:06, Abel Vesa <abel.vesa@...aro.org> wrote:
>
> From: Jagadeesh Kona <quic_jkona@...cinc.com>
>
> Add support for set and get hwmode callbacks to switch the GDSC between
> SW and HW modes. Currently, the GDSC is moved to HW control mode
> using HW_CTRL flag and if this flag is present, GDSC is moved to HW
> mode as part of GDSC enable itself. The intention is to keep the
> HW_CTRL flag functionality as is, since many older chipsets still use
> this flag.
>
> Introduce a new HW_CTRL_TRIGGER flag to switch the GDSC back and forth
> between HW/SW modes dynamically at runtime. If HW_CTRL_TRIGGER flag is
> present, register set_hwmode_dev callback to switch the GDSC mode which
> can be invoked from consumer drivers using dev_pm_genpd_set_hwmode
> function. Unlike HW_CTRL flag, HW_CTRL_TRIGGER won't move the GDSC to HW
> control mode as part of GDSC enable itself, GDSC will be moved to HW
> control mode only when consumer driver explicity calls
> dev_pm_genpd_set_hwmode to switch to HW mode. Also add the
> dev_pm_genpd_get_hwmode to allow the consumers to read the actual
> HW/SW mode from hardware.

Can we add two new flags:
- HW_CTRL_TRIGGER
- DEFAULT_HW_TRIGGER

And then define HW_CTRL as HW_CTRL_TRIGGER | DEFAULT_HW_TRIGGER ?

This way older platforms will keep existing behaviour, but can
gradually migrate to the new callbacks?

>
> Signed-off-by: Jagadeesh Kona <quic_jkona@...cinc.com>
> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> ---
>  drivers/clk/qcom/gdsc.c | 32 ++++++++++++++++++++++++++++++++
>  drivers/clk/qcom/gdsc.h |  1 +
>  2 files changed, 33 insertions(+)
>
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index 5358e28122ab..c763524cd5da 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -363,6 +363,34 @@ static int gdsc_disable(struct generic_pm_domain *domain)
>         return 0;
>  }
>
> +static int gdsc_set_hwmode(struct generic_pm_domain *domain, struct device *dev, bool mode)
> +{
> +       struct gdsc *sc = domain_to_gdsc(domain);
> +
> +       if (sc->rsupply && !regulator_is_enabled(sc->rsupply)) {
> +               pr_err("Cannot set mode while parent is disabled\n");
> +               return -EIO;
> +       }
> +
> +       return gdsc_hwctrl(sc, mode);
> +}
> +
> +static bool gdsc_get_hwmode(struct generic_pm_domain *domain, struct device *dev)
> +{
> +       struct gdsc *sc = domain_to_gdsc(domain);
> +       u32 val;
> +       int ret;
> +
> +       ret = regmap_read(sc->regmap, sc->gdscr, &val);
> +       if (ret)
> +               return ret;
> +
> +       if (val & HW_CONTROL_MASK)
> +               return true;
> +
> +       return false;
> +}
> +
>  static int gdsc_init(struct gdsc *sc)
>  {
>         u32 mask, val;
> @@ -451,6 +479,10 @@ static int gdsc_init(struct gdsc *sc)
>                 sc->pd.power_off = gdsc_disable;
>         if (!sc->pd.power_on)
>                 sc->pd.power_on = gdsc_enable;
> +       if (sc->flags & HW_CTRL_TRIGGER) {
> +               sc->pd.set_hwmode_dev = gdsc_set_hwmode;
> +               sc->pd.get_hwmode_dev = gdsc_get_hwmode;
> +       }
>
>         ret = pm_genpd_init(&sc->pd, NULL, !on);
>         if (ret)
> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
> index 803512688336..1e2779b823d1 100644
> --- a/drivers/clk/qcom/gdsc.h
> +++ b/drivers/clk/qcom/gdsc.h
> @@ -67,6 +67,7 @@ struct gdsc {
>  #define ALWAYS_ON      BIT(6)
>  #define RETAIN_FF_ENABLE       BIT(7)
>  #define NO_RET_PERIPH  BIT(8)
> +#define HW_CTRL_TRIGGER        BIT(9)
>         struct reset_controller_dev     *rcdev;
>         unsigned int                    *resets;
>         unsigned int                    reset_count;
>
> --
> 2.34.1
>


-- 
With best wishes
Dmitry