linux-kernel - Re: [PATCH v4 1/6] clk: sunxi-ng: div: Add support for fixed post-divider

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Message-ID: <20170627094607.2hkgzkycclboemvu@flea.lan>
Date:   Tue, 27 Jun 2017 11:46:07 +0200
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Priit Laes <plaes@...es.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Chen-Yu Tsai <wens@...e.org>,
        Russell King <linux@...linux.org.uk>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com, Jonathan Liu <net147@...il.com>
Subject: Re: [PATCH v4 1/6] clk: sunxi-ng: div: Add support for fixed
 post-divider

Hi!

On Sun, Jun 25, 2017 at 11:45:42PM +0300, Priit Laes wrote:
> SATA clock on sun4i/sun7i is of type (parent) / M / 6 where
> 6 is fixed post-divider.
> 
> Signed-off-by: Priit Laes <plaes@...es.org>
> ---
>  drivers/clk/sunxi-ng/ccu_div.c | 12 ++++++++++--
>  drivers/clk/sunxi-ng/ccu_div.h |  3 ++-
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/sunxi-ng/ccu_div.c b/drivers/clk/sunxi-ng/ccu_div.c
> index c0e5c10..de30e15 100644
> --- a/drivers/clk/sunxi-ng/ccu_div.c
> +++ b/drivers/clk/sunxi-ng/ccu_div.c
> @@ -62,8 +62,13 @@ static unsigned long ccu_div_recalc_rate(struct clk_hw *hw,
>  	parent_rate = ccu_mux_helper_apply_prediv(&cd->common, &cd->mux, -1,
>  						  parent_rate);
>  
> -	return divider_recalc_rate(hw, parent_rate, val, cd->div.table,
> -				   cd->div.flags);
> +	val = divider_recalc_rate(hw, parent_rate, val, cd->div.table,
> +				  cd->div.flags);
> +
> +	if (cd->common.features & CCU_FEATURE_FIXED_POSTDIV)
> +		val /= cd->fixed_post_div;
> +
> +	return val;
>  }
>  
>  static int ccu_div_determine_rate(struct clk_hw *hw,
> @@ -89,6 +94,9 @@ static int ccu_div_set_rate(struct clk_hw *hw, unsigned long rate,
>  	val = divider_get_val(rate, parent_rate, cd->div.table, cd->div.width,
>  			      cd->div.flags);
>  
> +	if (cd->common.features & CCU_FEATURE_FIXED_POSTDIV)
> +		val *= cd->fixed_post_div;
> +
>  	spin_lock_irqsave(cd->common.lock, flags);
>  
>  	reg = readl(cd->common.base + cd->common.reg);

You also need to adjust the round rate call back to take into account
the post divider before calling divider_round_rate_parent, and after
since that function can modify the parent_rate.

> diff --git a/drivers/clk/sunxi-ng/ccu_div.h b/drivers/clk/sunxi-ng/ccu_div.h
> index 08d0744..f3a5028 100644
> --- a/drivers/clk/sunxi-ng/ccu_div.h
> +++ b/drivers/clk/sunxi-ng/ccu_div.h
> @@ -86,9 +86,10 @@ struct ccu_div_internal {
>  struct ccu_div {
>  	u32			enable;
>  
> -	struct ccu_div_internal		div;
> +	struct ccu_div_internal	div;

Spurious change?

Thanks!
Maxime

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

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