Re: [PATCH v8 2/6] clk: renesas: rzv2h-cpg: Add support for DSI clocks

[Geert Uytterhoeven]

Hi Prabhakar,

On Wed, 3 Sept 2025 at 18:17, Prabhakar <prabhakar.csengg@xxxxxxxxx> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> Add support for PLLDSI and PLLDSI divider clocks.
>
> Introduce the `renesas-rzv2h-cpg-pll.h` header to centralize and share
> PLLDSI related data structures, limits, and algorithms between the
> RZ/V2H(P) CPG and DSI drivers.
>
> The DSI PLL is functionally similar to the CPG's PLLDSI, but has slightly
> different parameter limits and omits the programmable divider present in
> CPG. To ensure precise frequency calculations, especially for milliHz-level
> accuracy needed by the DSI driver, the shared algorithm allows both drivers
> to compute PLL parameters consistently using the same logic and input
> clock.
>
> Co-developed-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
> Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

> --- a/drivers/clk/renesas/rzv2h-cpg.c
> +++ b/drivers/clk/renesas/rzv2h-cpg.c

> +static int rzv2h_cpg_plldsi_div_determine_rate(struct clk_hw *hw,
> +                                              struct clk_rate_request *req)
> +{
> +       struct rzv2h_plldsi_div_clk *dsi_div = to_plldsi_div_clk(hw);
> +       struct pll_clk *pll_clk = to_pll(clk_hw_get_parent(hw));
> +       struct rzv2h_cpg_priv *priv = dsi_div->priv;
> +       struct rzv2h_pll_div_pars *dsi_params;
> +       struct rzv2h_pll_dsi_info *dsi_info;
> +       u64 rate_millihz;
> +
> +       dsi_info = &priv->pll_dsi_info[pll_clk->pll.instance];
> +       dsi_params = &dsi_info->pll_dsi_parameters;
> +
> +       rate_millihz = mul_u32_u32(req->rate, MILLI);
> +       if (rate_millihz == dsi_params->div.error_millihz + dsi_params->div.freq_millihz)
> +               goto exit_determine_rate;
> +
> +       if (!rzv2h_get_pll_dtable_pars(dsi_info->pll_dsi_limits, dsi_params, dsi_div->dtable,
> +                                      rate_millihz)) {
> +               dev_err(priv->dev,
> +                       "failed to determine rate for req->rate: %lu\n",
> +                       req->rate);
> +               return -EINVAL;
> +       }
> +
> +exit_determine_rate:
> +       req->rate = DIV_ROUND_CLOSEST_ULL(dsi_params->div.freq_millihz, MILLI);
> +       req->best_parent_rate = req->rate * dsi_params->div.divider_value;
> +       dsi_info->req_pll_dsi_rate = req->best_parent_rate;
> +
> +       return 0;
> +};

Unneeded semicolon (there are three more below).

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds