linux-kernel - Re: [PATCH] clk: use get

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Date:   Thu, 15 Feb 2018 16:22:21 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: use get_phase() if available

On Thu, 2018-02-15 at 11:28 +0100, Jerome Brunet wrote:
> When the get_phase() callback is available, we should use it
> instead of just relying the values cached, and assumed un-rounded,
> by the framework
> 
> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
> ---
> 
> Hi Mike, Stephen,
> 
> This changes applies on top of the phase fix I've sent [0]
> 
> [0]: https://lkml.kernel.org/r/20180215101958.22676-1-jbrunet@baylibre.com
> 
>  drivers/clk/clk.c | 25 ++++++++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index b33d362239e7..bcd6ec980903 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -2297,6 +2297,21 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
>  }
>  EXPORT_SYMBOL_GPL(clk_set_parent);
>  
> +static int clk_core_get_phase_nolock(struct clk_core *core)
> +{
> +	int ret;

+	if (!core)
+		return 0;

Forgot this, will add it the v2

> +
> +	if (!core->ops->get_phase)
> +		return core->phase;
> +
> +	/* Update the phase if the callback is available */
> +	ret = core->ops->get_phase(core->hw);
> +	if (ret >= 0)
> +		core->phase = ret;
> +
> +	return ret;
> +}
> +
>  static int clk_core_set_phase_nolock(struct clk_core *core, int degrees)
>  {
>  	int ret = -EINVAL;
> @@ -2314,12 +2329,16 @@ static int clk_core_set_phase_nolock(struct clk_core *core, int degrees)
>  	if (core->ops->set_phase)
>  		ret = core->ops->set_phase(core->hw, degrees);
>  
> -	if (!ret)
> +	if (!ret) {
>  		core->phase = degrees;
>  
> +		/* Read back the phase in case it got rounded */
> +		ret = clk_core_get_phase_nolock(core);
> +	}
> +
>  	trace_clk_set_phase_complete(core, degrees);
>  
> -	return ret;
> +	return ret > 0 ? 0 : ret;
>  }
>  
>  /**
> @@ -2375,7 +2394,7 @@ static int clk_core_get_phase(struct clk_core *core)
>  	int ret;
>  
>  	clk_prepare_lock();
> -	ret = core->phase;
> +	ret = clk_core_get_phase_nolock(core);
>  	clk_prepare_unlock();
>  
>  	return ret;