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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Tue, 28 Aug 2018 14:10:52 +0200
Message-ID: <CAMuHMdVqGBo4uXtzNeLyD4f3CKeQzmgdJNs4N2ZB7MDosU+t4w@mail.gmail.com>
Subject: vsps and channel indices (was: Re: [PATCH v3 1/2] arm64: dts:
 renesas: r8a77980: add FCPVD/VSPD/DU/LVDS support)
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
        Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
        Kieran Bingham <kbingham@kernel.org>
Cc: Simon Horman <horms@verge.net.au>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>
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Hi Sergei, Laurent, Kieran,

On Wed, Jun 13, 2018 at 10:11 PM Sergei Shtylyov
<sergei.shtylyov@cogentembedded.com> wrote:
> Describe the interconnected FCPVD0, VSPD0, DU, and LVDS0 devices in the
> R8A77980 device tree...
>
> Based on the original (and large) patch by Vladimir Barinov.
>
> Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> --- renesas.orig/arch/arm64/boot/dts/renesas/r8a77980.dtsi
> +++ renesas/arch/arm64/boot/dts/renesas/r8a77980.dtsi

> +               du: display@feb00000 {
> +                       compatible = "renesas,du-r8a77980",
> +                                    "renesas,du-r8a77970";
> +                       reg = <0 0xfeb00000 0 0x80000>;
> +                       interrupts = <GIC_SPI 256 IRQ_TYPE_LEVEL_HIGH>;
> +                       clocks = <&cpg CPG_MOD 724>;
> +                       clock-names = "du.0";
> +                       power-domains = <&sysc R8A77980_PD_ALWAYS_ON>;
> +                       resets = <&cpg 724>;
> +                       vsps = <&vspd0>;

According to the bindings, the vsps property should also contain a
channel index.

Laurent added the indices to r8a7795.dtsi, but r8a7795-es.dtsi overrides
that with a version without the indices.
Kieran included the indices when adding DU support for r8a77965 and
r8a77995.

r8a7796.dtsi, r8a77970.dtsi, and r8a77980.dtsi lack the indices.

Commit fd57d77f9c649cf9 ("dt-bindings: display: rcar-du: Add a VSP channel
index to the vsps DT property") says a backwards-compatibility mode can be
implemented, but I fail to see how this can work, as rcar_du_vsps_init()
will just return an error, which is propagated.

What am I missing?

Thanks!

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