linux-kernel - Re: [PATCH 3/3] clk: qcom: gdsc: Add support to poll CFG register to check GDSC state

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Message-ID: <152303280515.143116.7021012753371503067@swboyd.mtv.corp.google.com>
Date:   Fri, 06 Apr 2018 09:40:05 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Taniya Das <tdas@...eaurora.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Odelu Kukatla <okukatla@...eaurora.org>,
        Amit Nischal <anischal@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Taniya Das <tdas@...eaurora.org>
Subject: Re: [PATCH 3/3] clk: qcom: gdsc: Add support to poll CFG register to check
 GDSC state

Quoting Taniya Das (2018-04-02 03:45:45)
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index e89584e..e0c83ba 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -83,6 +88,38 @@ static int gdsc_poll_status(struct gdsc *sc, unsigned int reg, bool en)
>         return -ETIMEDOUT;
>  }
> 
> +static int gdsc_is_enabled_by_poll_cfg_reg(struct gdsc *sc, bool en)
> +{
> +       u32 val;
> +       int ret;
> +
> +       ret = regmap_read(sc->regmap, sc->gdscr + CFG_GDSCR_OFFSET, &val);
> +       if (ret)
> +               return ret;
> +
> +       if (en)
> +               return !!(val & GDSC_POWER_UP_COMPLETE);
> +       else
> +               return !(val & GDSC_POWER_DOWN_COMPLETE);

Make this into

	if (en)
		return ...

	return ...

> +}
> +
> +static int gdsc_poll_cfg_status(struct gdsc *sc, bool en)
> +{
> +       ktime_t start = ktime_get();
> +       ktime_t timeout =
> +               (sc->flags & GDS_TIMEOUT) ? TIMEOUT_US_GDS : TIMEOUT_US;
> +
> +       do {
> +               if (gdsc_is_enabled_by_poll_cfg_reg(sc, en) == en)
> +                       return 0;
> +       } while (ktime_us_delta(ktime_get(), start) < timeout);
> +
> +       if (gdsc_is_enabled_by_poll_cfg_reg(sc, en) == en)
> +               return 0;
> +
> +       return -ETIMEDOUT;
> +}
> +
>  static int gdsc_toggle_logic(struct gdsc *sc, bool en)
>  {
>         int ret;
> @@ -106,6 +143,9 @@ static int gdsc_toggle_logic(struct gdsc *sc, bool en)
>                 return 0;
>         }
> 
> +       if (sc->flags & POLL_CFG_GDSCR)
> +               return gdsc_poll_cfg_status(sc, en);
> +
>         if (sc->gds_hw_ctrl) {
>                 status_reg = sc->gds_hw_ctrl;
>                 /*
> @@ -258,8 +298,12 @@ static int gdsc_disable(struct generic_pm_domain *domain)
>                  */
>                 udelay(1);
> 
> -               reg = sc->gds_hw_ctrl ? sc->gds_hw_ctrl : sc->gdscr;
> -               ret = gdsc_poll_status(sc, reg, true);
> +               if (sc->flags & POLL_CFG_GDSCR) {
> +                       ret = gdsc_poll_cfg_status(sc, true);
> +               } else {
> +                       reg = sc->gds_hw_ctrl ? sc->gds_hw_ctrl : sc->gdscr;
> +                       ret = gdsc_poll_status(sc, reg, true);
> +               }

Maybe this can be pushed into the gdsc_poll_status() function so that
we can keep the "how do we poll status bit" logic in one place.

>                 if (ret)
>                         return ret;
>         }