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SubjectRe: [PATCH 1/3] clk: divider: Fix best div calculation for power-of-two and table dividers
Date
Quoting Maxime COQUELIN (2014-01-29 08:24:06)
> The divider returned by clk_divider_bestdiv() is likely to be invalid in case
> of power-of-two and table dividers when CLK_SET_RATE_PARENT flag isn't set.
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>

I've taken this into clk-fixes for 3.15-rcX.

Thanks,
Mike

> ---
> drivers/clk/clk-divider.c | 37 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index 5543b7d..2137d58 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -144,6 +144,37 @@ static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
> return true;
> }
>
> +static int _round_up_table(const struct clk_div_table *table, int div)
> +{
> + const struct clk_div_table *clkt;
> + int up = _get_table_maxdiv(table);
> +
> + for (clkt = table; clkt->div; clkt++) {
> + if (clkt->div == div)
> + return clkt->div;
> + else if (clkt->div < div)
> + continue;
> +
> + if ((clkt->div - div) < (up - div))
> + up = clkt->div;
> + }
> +
> + return up;
> +}
> +
> +static int _div_round_up(struct clk_divider *divider,
> + unsigned long parent_rate, unsigned long rate)
> +{
> + int div = DIV_ROUND_UP(parent_rate, rate);
> +
> + if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
> + div = __roundup_pow_of_two(div);
> + if (divider->table)
> + div = _round_up_table(divider->table, div);
> +
> + return div;
> +}
> +
> static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
> unsigned long *best_parent_rate)
> {
> @@ -159,7 +190,7 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
>
> if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
> parent_rate = *best_parent_rate;
> - bestdiv = DIV_ROUND_UP(parent_rate, rate);
> + bestdiv = _div_round_up(divider, parent_rate, rate);
> bestdiv = bestdiv == 0 ? 1 : bestdiv;
> bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
> return bestdiv;
> @@ -219,6 +250,10 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
> u32 val;
>
> div = parent_rate / rate;
> +
> + if (!_is_valid_div(divider, div))
> + return -EINVAL;
> +
> value = _get_val(divider, div);
>
> if (value > div_mask(divider))
> --
> 1.7.9.5
>


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