Subject: [PATCH v3 01/11] clk: composite: support determine_rate using rate_ops->round_rate + mux_ops->set_parent

From: [email-masked] (Boris BREZILLON)
Date: Mon, 26 May 2014 11:24:44 +0200

Hello Heiko,

On 23/05/2014 21:33, Heiko St?bner wrote:
> From: Boris BREZILLON <[email-masked]>
>
> In case the rate_hw does not implement determine_rate, but only round_rate
> we fallback to best_parent selection if mux_hw is present and support
> reparenting.
>
> Signed-off-by: Boris BREZILLON <[email-masked]>
>
> This also fixes a rate calculation problem when using the standard div and
> mux ops, as in this case currently only the mux->determine_rate is used
> in the composite rate calculation.
> [fixed the output to actually return a rate instead of the diff]
Sorry for the delay and thanks for fixing this.

Anyway, when I first proposed this patch, Emilio (added in Cc) told me
this should not be automatically done by the composite clk driver, and
the driver should instead provide the determine_rate function.

Mike, any opinion on this patch ?

Best Regards,

Boris

> Signed-off-by: Heiko Stuebner <[email-masked]>
> ---
>  drivers/clk/clk-composite.c | 51 ++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c
> index 57a078e..0a4cd21 100644
> --- a/drivers/clk/clk-composite.c
> +++ b/drivers/clk/clk-composite.c
> @@ -64,11 +64,59 @@ static long clk_composite_determine_rate(struct clk_hw *hw, unsigned long rate,
>  	const struct clk_ops *mux_ops = composite->mux_ops;
>  	struct clk_hw *rate_hw = composite->rate_hw;
>  	struct clk_hw *mux_hw = composite->mux_hw;
> +	struct clk *parent;
> +	unsigned long parent_rate;
> +	long tmp_rate, best_rate;
> +	unsigned long rate_diff;
> +	unsigned long best_rate_diff = ULONG_MAX;
> +	int i;
>  
>  	if (rate_hw && rate_ops && rate_ops->determine_rate) {
>  		rate_hw->clk = hw->clk;
>  		return rate_ops->determine_rate(rate_hw, rate, best_parent_rate,
>  						best_parent_p);
> +	} else if (rate_hw && rate_ops && rate_ops->round_rate &&
> +		   mux_hw && mux_ops && mux_ops->set_parent) {
> +		*best_parent_p = NULL;
> +
> +		if (__clk_get_flags(hw->clk) & CLK_SET_RATE_NO_REPARENT) {
> +			*best_parent_p = clk_get_parent(mux_hw->clk);
> +			*best_parent_rate = __clk_get_rate(*best_parent_p);
> +
> +			return rate_ops->round_rate(rate_hw, rate,
> +						    best_parent_rate);
> +		}
> +
> +		for (i = 0; i < __clk_get_num_parents(mux_hw->clk); i++) {
> +			parent = clk_get_parent_by_index(mux_hw->clk, i);
> +			if (!parent)
> +				continue;
> +
> +			parent_rate = __clk_get_rate(parent);
> +
> +			tmp_rate = rate_ops->round_rate(rate_hw, rate,
> +							&parent_rate);
> +			if (tmp_rate < 0)
> +				continue;
> +
> +			if (tmp_rate < rate)
> +				rate_diff = rate - tmp_rate;
> +			else
> +				rate_diff = tmp_rate - rate;
> +
> +			if (!rate_diff || !*best_parent_p
> +				       || best_rate_diff > rate_diff) {
> +				*best_parent_p = parent;
> +				*best_parent_rate = parent_rate;
> +				best_rate_diff = rate_diff;
> +				best_rate = tmp_rate;
> +			}
> +
> +			if (!rate_diff)
> +				return rate;
> +		}
> +
> +		return best_rate;
>  	} else if (mux_hw && mux_ops && mux_ops->determine_rate) {
>  		mux_hw->clk = hw->clk;
>  		return mux_ops->determine_rate(mux_hw, rate, best_parent_rate,
> @@ -196,7 +244,8 @@ struct clk *clk_register_composite(struct device *dev, const char *name,
>  		composite->rate_hw = rate_hw;
>  		composite->rate_ops = rate_ops;
>  		clk_composite_ops->recalc_rate = clk_composite_recalc_rate;
> -		if (rate_ops->determine_rate)
> +		if (rate_ops->determine_rate ||
> +		    (rate_ops->round_rate && clk_composite_ops->set_parent))
>  			clk_composite_ops->determine_rate = clk_composite_determine_rate;
>  	}
>  

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com