linux-kernel - Re: [PATCH 01/11] clk: sunxi-ng: mux: Fix determine

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Date:   Thu, 26 Jan 2017 10:55:23 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH 01/11] clk: sunxi-ng: mux: Fix determine_rate for mux
 clocks with pre-dividers

Hi Chen-Yu,

On Tue, Jan 24, 2017 at 10:32:20AM +0800, Chen-Yu Tsai wrote:
> The determine_rate helper used ccu_mux_helper_adjust_parent_for_prediv()
> to adjust the parent_rate to account for pre-dividers, but then passed
> the pristine parent clock rate from clk_hw_get_rate() to the round()
> callback, thereby ignoring the pre-divider adjustment. In addition,
> it was saving the adjusted parent rate back into struct
> clk_rate_request.
> 
> This patch fixes this by saving the pristine parent clock rate, and
> adding a copy that is adjusted and passed to the round() callback.
> The pristine copy, if it is the best solution, would be saved back
> to struct clk_rate_request.
> 
> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
> ---
>  drivers/clk/sunxi-ng/ccu_mux.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/sunxi-ng/ccu_mux.c b/drivers/clk/sunxi-ng/ccu_mux.c
> index 858a48621631..3445041894e7 100644
> --- a/drivers/clk/sunxi-ng/ccu_mux.c
> +++ b/drivers/clk/sunxi-ng/ccu_mux.c
> @@ -71,7 +71,7 @@ int ccu_mux_helper_determine_rate(struct ccu_common *common,
>  	unsigned int i;
>  
>  	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
> -		unsigned long tmp_rate, parent_rate;
> +		unsigned long tmp_rate, parent_rate, adj_parent_rate;
>  		struct clk_hw *parent;
>  
>  		parent = clk_hw_get_parent_by_index(hw, i);
> @@ -79,10 +79,11 @@ int ccu_mux_helper_determine_rate(struct ccu_common *common,
>  			continue;
>  
>  		parent_rate = clk_hw_get_rate(parent);
> +		adj_parent_rate = parent_rate;
>  		ccu_mux_helper_adjust_parent_for_prediv(common, cm, i,
> -							&parent_rate);
> +							&adj_parent_rate);
>  
> -		tmp_rate = round(cm, clk_hw_get_rate(parent), req->rate, data);
> +		tmp_rate = round(cm, parent_rate, req->rate, data);

Shouldn't you use the adjusted rate here too?

Thanks,
Maxime

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

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