linux-kernel - Re: [PATCH 1/4] clk: qcom: gdsc: Add support to enable/disable the clocks with GDSC

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Date:   Sun, 08 Jul 2018 22:34:35 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Amit Nischal <anischal@...eaurora.org>,
        Michael Turquette <mturquette@...libre.com>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Odelu Kukatla <okukatla@...eaurora.org>,
        Taniya Das <tdas@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Amit Nischal <anischal@...eaurora.org>
Subject: Re: [PATCH 1/4] clk: qcom: gdsc: Add support to enable/disable the clocks
 with GDSC

Quoting Amit Nischal (2018-06-06 04:41:45)
> For some of the GDSCs, there is a requirement to enable/disable the
> few clocks before turning on/off the gdsc power domain. Add support

Why is there a requirement? Do the clks need to be in hw control mode or
they can't be turned off when the GDSC is off? It's hard for me to
understand with these vague statements.

> for the same by specifying a list of clk_hw pointers per gdsc and
> enable/disable them along with power domain on/off callbacks.
> 
> Signed-off-by: Amit Nischal <anischal@...eaurora.org>
> ---
>  drivers/clk/qcom/gdsc.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/qcom/gdsc.h |  5 +++++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index a077133..b6adca1 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -12,6 +12,8 @@
>   */
> 
>  #include <linux/bitops.h>
> +#include <linux/clk.h>

Ugh.

> +#include <linux/clk-provider.h>

Both, really?

>  #include <linux/delay.h>
>  #include <linux/err.h>
>  #include <linux/jiffies.h>
> @@ -208,11 +210,41 @@ static inline void gdsc_assert_reset_aon(struct gdsc *sc)
>         regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
>                            GMEM_RESET_MASK, 0);
>  }
> +
> +static int gdsc_clk_prepare_enable(struct gdsc *sc)
> +{
> +       int i, ret;
> +
> +       for (i = 0; i < sc->clk_count; i++) {
> +               ret = clk_prepare_enable(sc->clk_hws[i]->clk);
> +               if (ret) {
> +                       for (i--; i >= 0; i--)
> +                               clk_disable_unprepare(sc->clk_hws[i]->clk);
> +                       return ret;
> +               }
> +       }
> +       return 0;
> +}
> +

Looks an awful lot like bulk_enable clk API.