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Subject: Re: [PATCH v8 10/21] clk: tegra: clk-super: Add restore-context
 support
To:     Sowjanya Komatineni <skomatineni@nvidia.com>,
        thierry.reding@gmail.com, jonathanh@nvidia.com, tglx@linutronix.de,
        jason@lakedaemon.net, marc.zyngier@arm.com,
        linus.walleij@linaro.org, stefan@agner.ch, mark.rutland@arm.com
Cc:     pdeschrijver@nvidia.com, pgaikwad@nvidia.com, sboyd@kernel.org,
        linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org,
        jckuo@nvidia.com, josephl@nvidia.com, talho@nvidia.com,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
        mperttunen@nvidia.com, spatra@nvidia.com, robh+dt@kernel.org,
        devicetree@vger.kernel.org, rjw@rjwysocki.net,
        viresh.kumar@linaro.org, linux-pm@vger.kernel.org
References: <1565308020-31952-1-git-send-email-skomatineni@nvidia.com>
 <1565308020-31952-11-git-send-email-skomatineni@nvidia.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <4e33bad9-8d5a-dcd7-c75e-db5843c9be4a@gmail.com>
Date:   Fri, 9 Aug 2019 15:17:25 +0300
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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@nvidia.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,
>