Re: [PATCH 2/2] ARM: tegra: Move panels to AUX bus

[Doug Anderson <dianders@chromium.org>]

Hi,

On Mon, Dec 20, 2021 at 2:49 AM Thierry Reding <thierry.reding@gmail.com> wrote:
>
> From: Thierry Reding <treding@nvidia.com>
>
> Move the eDP panel on Venice 2 and Nyan boards into the corresponding
> AUX bus device tree node. This allows us to avoid a nasty circular
> dependency that would otherwise be created between the DPAUX and panel
> nodes via the DDC/I2C phandle.
>
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  arch/arm/boot/dts/tegra124-nyan-big.dts   | 15 +++++++++------
>  arch/arm/boot/dts/tegra124-nyan-blaze.dts | 15 +++++++++------
>  arch/arm/boot/dts/tegra124-venice2.dts    | 14 +++++++-------
>  3 files changed, 25 insertions(+), 19 deletions(-)
>
> diff --git a/arch/arm/boot/dts/tegra124-nyan-big.dts b/arch/arm/boot/dts/tegra124-nyan-big.dts
> index 1d2aac2cb6d0..fdc1d64dfff9 100644
> --- a/arch/arm/boot/dts/tegra124-nyan-big.dts
> +++ b/arch/arm/boot/dts/tegra124-nyan-big.dts
> @@ -13,12 +13,15 @@ / {
>                      "google,nyan-big-rev1", "google,nyan-big-rev0",
>                      "google,nyan-big", "google,nyan", "nvidia,tegra124";
>
> -       panel: panel {
> -               compatible = "auo,b133xtn01";
> -
> -               power-supply = <&vdd_3v3_panel>;

You remove the "power-supply" line here but don't add it below. Isn't
that a problem? power-supply for the panel is listed as "required" in
the panel dt bindings so I presume this will increase validation
warnings?


> -               backlight = <&backlight>;
> -               ddc-i2c-bus = <&dpaux>;
> +       host1x@50000000 {
> +               dpaux@545c0000 {

Optional nit: on other SoC dts files I've always had the policy to try
to avoid replicating hierarchies like this (host1x@50000000 =>
dpaux@545c0000). Instead I'd express this as:

&dpaux {
  aux-bux {
    panel: panel {
      ...
    };
  };
};


> +                       aux-bus {
> +                               panel: panel {
> +                                       compatible = "auo,b133xtn01";
> +                                       backlight = <&backlight>;

nit: In theory the "backlight" could go in tegra124-nyan.dtsi, right?
Then you just need to override the compatible...


-Doug