Re: [PATCH 1/2] drm: rcar-du: Add Standby Mode support

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Hoan,

On Fri, Dec 14, 2018 at 8:25 AM Nguyen An Hoan <na-hoan@jinso.co.jp> wrote:
> From: Hoan Nguyen An <na-hoan@jinso.co.jp>
>
> Add function support for Module Standby Mode
>
> Signed-off-by: Hoan Nguyen An <na-hoan@jinso.co.jp>

Thanks for your patch!

> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -651,6 +651,32 @@ static void rcar_du_crtc_stop(struct rcar_du_crtc *rcrtc)
>         rcar_du_group_start_stop(rcrtc->group, false);
>  }
>
> +int rcar_du_crtc_standby(struct rcar_du_crtc *rcrtc)
> +{
> +       u32 val_reg;
> +       unsigned int i = 0;
> +
> +       /* Enter Standby mode */
> +       rcar_du_crtc_dsysr_clr_set(rcrtc, DSYSR_DRES | DSYSR_DEN, 0);
> +
> +       for(i = 100; i > 0; i--)
> +       {
> +               val_reg = rcar_du_crtc_read(rcrtc, DSSR);
> +               if(!(val_reg & DSSR_VBK))
> +                       break;
> +               udelay(10);
> +       }
> +
> +       if(!(i > 0))
> +               return -ETIMEDOUT;
> +
> +       /* Stop clock */
> +       clk_set_rate(rcrtc->extclock, 0);
> +       clk_set_rate(rcrtc->clock, 0);

That's not the API to stop a clock.
Why do you set the clock rates to 0?

> +
> +       return 0;
> +}

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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