linux-kernel - Re: [PATCH RFC v1 2/3] clk: meson: regmap: switch to determine

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Message-ID: <1jr1i41o0p.fsf@starbuckisacylon.baylibre.com>
Date:   Tue, 18 May 2021 09:47:50 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        mturquette@...libre.com, sboyd@...nel.org, narmstrong@...libre.com,
        linux-clk@...r.kernel.org
Cc:     khilman@...libre.com, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RFC v1 2/3] clk: meson: regmap: switch to determine_rate
 for the dividers


On Mon 17 May 2021 at 22:37, Martin Blumenstingl <martin.blumenstingl@...glemail.com> wrote:

> This increases the maxmium supported frequency on 32-bit systems from
> 2^31 (signed long as used by clk_ops.round_rate, maximum value:
> approx. 2.14GHz) to 2^32 (unsigned long as used by
> clk_ops.determine_rate, maximum value: approx. 4.29GHz).
> On Meson8/8b/8m2 the HDMI PLL and it's OD (post-dividers) are
> capable of running at up to 2.97GHz. So switch the divider
> implementation in clk-regmap to clk_ops.determine_rate to support these
> higher frequencies on 32-bit systems.
>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

Reviewed-by: Jerome Brunet <jbrunet@...libre.com>

> ---
>  drivers/clk/meson/clk-regmap.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/clk/meson/clk-regmap.c b/drivers/clk/meson/clk-regmap.c
> index dcd1757cc5df..8ad8977cf1c2 100644
> --- a/drivers/clk/meson/clk-regmap.c
> +++ b/drivers/clk/meson/clk-regmap.c
> @@ -75,8 +75,8 @@ static unsigned long clk_regmap_div_recalc_rate(struct clk_hw *hw,
>  				   div->width);
>  }
>  
> -static long clk_regmap_div_round_rate(struct clk_hw *hw, unsigned long rate,
> -				      unsigned long *prate)
> +static int clk_regmap_div_determine_rate(struct clk_hw *hw,
> +					 struct clk_rate_request *req)
>  {
>  	struct clk_regmap *clk = to_clk_regmap(hw);
>  	struct clk_regmap_div_data *div = clk_get_regmap_div_data(clk);
> @@ -87,18 +87,17 @@ static long clk_regmap_div_round_rate(struct clk_hw *hw, unsigned long rate,
>  	if (div->flags & CLK_DIVIDER_READ_ONLY) {
>  		ret = regmap_read(clk->map, div->offset, &val);
>  		if (ret)
> -			/* Gives a hint that something is wrong */
> -			return 0;
> +			return ret;
>  
>  		val >>= div->shift;
>  		val &= clk_div_mask(div->width);
>  
> -		return divider_ro_round_rate(hw, rate, prate, div->table,
> -					     div->width, div->flags, val);
> +		return divider_ro_determine_rate(hw, req, div->table,
> +						 div->width, div->flags, val);
>  	}
>  
> -	return divider_round_rate(hw, rate, prate, div->table, div->width,
> -				  div->flags);
> +	return divider_determine_rate(hw, req, div->table, div->width,
> +				      div->flags);
>  }
>  
>  static int clk_regmap_div_set_rate(struct clk_hw *hw, unsigned long rate,
> @@ -123,14 +122,14 @@ static int clk_regmap_div_set_rate(struct clk_hw *hw, unsigned long rate,
>  
>  const struct clk_ops clk_regmap_divider_ops = {
>  	.recalc_rate = clk_regmap_div_recalc_rate,
> -	.round_rate = clk_regmap_div_round_rate,
> +	.determine_rate = clk_regmap_div_determine_rate,
>  	.set_rate = clk_regmap_div_set_rate,
>  };
>  EXPORT_SYMBOL_GPL(clk_regmap_divider_ops);
>  
>  const struct clk_ops clk_regmap_divider_ro_ops = {
>  	.recalc_rate = clk_regmap_div_recalc_rate,
> -	.round_rate = clk_regmap_div_round_rate,
> +	.determine_rate = clk_regmap_div_determine_rate,
>  };
>  EXPORT_SYMBOL_GPL(clk_regmap_divider_ro_ops);