linux-kernel - Re: [PATCH v8 10/21] clk: tegra: clk-super: Add restore-context support

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Date:   Fri, 9 Aug 2019 15:17:25 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, tglx@...utronix.de,
        jason@...edaemon.net, marc.zyngier@....com,
        linus.walleij@...aro.org, stefan@...er.ch, mark.rutland@....com
Cc:     pdeschrijver@...dia.com, pgaikwad@...dia.com, sboyd@...nel.org,
        linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
        jckuo@...dia.com, josephl@...dia.com, talho@...dia.com,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        mperttunen@...dia.com, spatra@...dia.com, robh+dt@...nel.org,
        devicetree@...r.kernel.org, rjw@...ysocki.net,
        viresh.kumar@...aro.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v8 10/21] clk: tegra: clk-super: Add restore-context
 support

09.08.2019 2:46, Sowjanya Komatineni пишет:
> This patch implements restore_context for clk_super_mux and clk_super.
> 
> During system supend, core power goes off the and context of Tegra
> CAR registers is lost.
> 
> So on system resume, context of super clock registers are restored
> to have them in same state as before suspend.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
> ---
>  drivers/clk/tegra/clk-super.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/clk/tegra/clk-super.c b/drivers/clk/tegra/clk-super.c
> index e2a1e95a8db7..74c9e913e41c 100644
> --- a/drivers/clk/tegra/clk-super.c
> +++ b/drivers/clk/tegra/clk-super.c
> @@ -124,9 +124,18 @@ static int clk_super_set_parent(struct clk_hw *hw, u8 index)
>  	return err;
>  }
>  
> +static void clk_super_mux_restore_context(struct clk_hw *hw)
> +{
> +	struct clk_hw *parent = clk_hw_get_parent(hw);
> +	int parent_id = clk_hw_get_parent_index(hw, parent);
> +
> +	clk_super_set_parent(hw, parent_id);

All Super clocks have a divider, including the "MUX". Thus I'm wondering
if there is a chance that divider's configuration may differ on resume
from what it was on suspend.

> +}
> +
>  static const struct clk_ops tegra_clk_super_mux_ops = {
>  	.get_parent = clk_super_get_parent,
>  	.set_parent = clk_super_set_parent,
> +	.restore_context = clk_super_mux_restore_context,
>  };
>  
>  static long clk_super_round_rate(struct clk_hw *hw, unsigned long rate,
> @@ -162,12 +171,24 @@ static int clk_super_set_rate(struct clk_hw *hw, unsigned long rate,
>  	return super->div_ops->set_rate(div_hw, rate, parent_rate);
>  }
>  
> +static void clk_super_restore_context(struct clk_hw *hw)
> +{
> +	struct tegra_clk_super_mux *super = to_clk_super_mux(hw);
> +	struct clk_hw *div_hw = &super->frac_div.hw;
> +	struct clk_hw *parent = clk_hw_get_parent(hw);
> +	int parent_id = clk_hw_get_parent_index(hw, parent);
> +
> +	super->div_ops->restore_context(div_hw);
> +	clk_super_set_parent(hw, parent_id);
> +}
> +
>  const struct clk_ops tegra_clk_super_ops = {
>  	.get_parent = clk_super_get_parent,
>  	.set_parent = clk_super_set_parent,
>  	.set_rate = clk_super_set_rate,
>  	.round_rate = clk_super_round_rate,
>  	.recalc_rate = clk_super_recalc_rate,
> +	.restore_context = clk_super_restore_context,
>  };
>  
>  struct clk *tegra_clk_register_super_mux(const char *name,
>