[PATCH 22/31] clk: mediatek: add CLK_BYPASS_XTAL flag to allow bypassing searching clock parent of xtal clock

[Simon Glass]

Hi Weijie,

On Wed, 3 Aug 2022 at 21:39, Weijie Gao <weijie.gao at mediatek.com> wrote:
>
> The mtk clock framework in u-boot uses array index for searching clock
> parent (kernel uses strings for search), so we need to specify a special
> clock with ID=0 for CLK_XTAL in u-boot.
>
> In the mt7622/mt7629 clock tree, the clocks with ID=0 never call
> mtk_topckgen_get_mux_rate, adn return xtal clock directly. This what we
> expected.
>
> However for newer chips, they may have some clocks with ID=0 not
> representing the xtal clock and still needs mtk_topckgen_get_mux_rate be
> called. Current logic will make entire clock driver not working.
>
> This patch adds a flag to indicate that whether a clock driver needs clocks
> with ID=0 to call mtk_topckgen_get_mux_rate.
>
> Signed-off-by: Weijie Gao <weijie.gao at mediatek.com>
> ---
>  drivers/clk/mediatek/clk-mtk.c | 5 ++++-
>  drivers/clk/mediatek/clk-mtk.h | 3 +++
>  2 files changed, 7 insertions(+), 1 deletion(-)

Reviewed-by: Simon Glass <sjg at chromium.org>

>
> diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
> index d43b8a0648..d99ea55df0 100644
> --- a/drivers/clk/mediatek/clk-mtk.c
> +++ b/drivers/clk/mediatek/clk-mtk.c
> @@ -314,12 +314,15 @@ static ulong mtk_topckgen_get_mux_rate(struct clk
>  *clk, u32 off)
>         struct mtk_clk_priv *priv = dev_get_priv(clk->dev);
>         const struct mtk_composite *mux = &priv->tree->muxes[off];
>         u32 index;
> +       u32 flag = 0;
>
>         index = readl(priv->base + mux->mux_reg);
>         index &= mux->mux_mask << mux->mux_shift;
>         index = index >> mux->mux_shift;
>
> -       if (mux->parent[index])
> +       if (mux->parent[index] == CLK_XTAL && priv->tree->flags & CLK_BYPASS_XTAL)
> +               flag = 1;
> +       if (mux->parent[index] > 0 || flag == 1)
>                 return mtk_clk_find_parent_rate(clk, mux->parent[index],
>                                                 NULL);
>
> diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
> index 95a23d14a8..0ab6912bf0 100644
> --- a/drivers/clk/mediatek/clk-mtk.h
> +++ b/drivers/clk/mediatek/clk-mtk.h
> @@ -11,6 +11,8 @@
>  #define CLK_XTAL                       0
>  #define MHZ                            (1000 * 1000)
>
> +#define CLK_BYPASS_XTAL                        BIT(0)
> +
>  #define HAVE_RST_BAR                   BIT(0)
>  #define CLK_DOMAIN_SCPSYS              BIT(0)
>  #define CLK_MUX_SETCLR_UPD             BIT(1)
> @@ -197,6 +199,7 @@ struct mtk_clk_tree {
>         const struct mtk_fixed_clk *fclks;
>         const struct mtk_fixed_factor *fdivs;
>         const struct mtk_composite *muxes;
> +       u32 flags;

This needs a comment as to what the flags mean

>  };
>
>  struct mtk_clk_priv {
> --
> 2.17.1
>

Regards,
Simon