Quoting Devi Priya (2023-09-01 00:00:41)
> The round_rate() API returns a long value as the errors are reported using
> negative error codes. This leads to long overflow when the clock rate
> exceeds 2GHz.As the clock controller treats the clock rate above signed
> long max as an error, use determine_rate in place of round_rate as the
> determine_rate API does not possess such limitations.
Does this fix something, or is it preparing for PLLs that run faster
than 2GHz?
>
> Signed-off-by: Devi Priya <quic_devipriy@xxxxxxxxxxx>
> ---
> Changes in V2:
> - Updated divider_round_rate to divider_determine_rate as
> suggested by Stephen Boyd.
>
> drivers/clk/qcom/clk-alpha-pll.c | 125 +++++++++++++++++--------------
> 1 file changed, 68 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> index 1c2a72840cd2..de2b7e2784ec 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.c
> +++ b/drivers/clk/qcom/clk-alpha-pll.c
> @@ -2353,22 +2362,24 @@ static unsigned long clk_rivian_evo_pll_recalc_rate(struct clk_hw *hw,
> return parent_rate * l;
> }
>
> -static long clk_rivian_evo_pll_round_rate(struct clk_hw *hw, unsigned long rate,
> - unsigned long *prate)
> +static int clk_rivian_evo_pll_determine_rate(struct clk_hw *hw,
> + struct clk_rate_request *req)
> {
> struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
> unsigned long min_freq, max_freq;
> u32 l;
> u64 a;
>
> - rate = alpha_pll_round_rate(rate, *prate, &l, &a, 0);
> - if (!pll->vco_table || alpha_pll_find_vco(pll, rate))
> - return rate;
> + req->rate = alpha_pll_round_rate(req->rate, req->best_parent_rate,
> + &l, &a, 0);
> + if (!pll->vco_table || alpha_pll_find_vco(pll, req->rate))
> + return 0;
>
> min_freq = pll->vco_table[0].min_freq;
> max_freq = pll->vco_table[pll->num_vco - 1].max_freq;
>
> - return clamp(rate, min_freq, max_freq);
> + req->rate = clamp(req->rate, min_freq, max_freq);
> + return 0;
> }
Is this any different from clk_alpha_pll_determine_rate()? I think the
only difference is alpha_pll_width, which could probably be some
argument passed to an alpha_pll_determine_rate() function that does the
internal clamping. It could also take a struct clk_rate_request then so
that we don't pass individual members of that struct.
