Re: [PATCH V4 3/6] drm: bridge: samsung-dsim: Fetch pll-clock-frequency automatically

[Adam Ford]

On Fri, May 5, 2023 at 8:09 PM Adam Ford <aford173@xxxxxxxxx> wrote:
>
> Make the pll-clock-frequency optional.  If it's present, use it
> to maintain backwards compatibility with existing hardware.  If it
> is absent, read clock rate of "sclk_mipi" to determine the rate.
>
> Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
> Tested-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
> Tested-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> Reviewed-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>


Sorry for the noise.  I forgot to merge in the suggested updates for
the messages so they don't look like errors.  A V5 is coming once I
merge and test the changes.

adam
> ---
>  drivers/gpu/drm/bridge/samsung-dsim.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index bf4b33d2de76..2dc02a9e37c0 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1726,12 +1726,20 @@ static int samsung_dsim_parse_dt(struct samsung_dsim *dsi)
>  {
>         struct device *dev = dsi->dev;
>         struct device_node *node = dev->of_node;
> +       struct clk *pll_clk;
>         int ret;
>
>         ret = samsung_dsim_of_read_u32(node, "samsung,pll-clock-frequency",
>                                        &dsi->pll_clk_rate);
> -       if (ret < 0)
> -               return ret;
> +
> +       /* If it doesn't exist, read it from the clock instead of failing */
> +       if (ret < 0) {
> +               pll_clk = devm_clk_get(dev, "sclk_mipi");
> +               if (!IS_ERR(pll_clk))
> +                       dsi->pll_clk_rate = clk_get_rate(pll_clk);
> +               else
> +                       return PTR_ERR(pll_clk);
> +       }
>
>         ret = samsung_dsim_of_read_u32(node, "samsung,burst-clock-frequency",
>                                        &dsi->burst_clk_rate);
> --
> 2.39.2
>