Re: [PATCH] arm64: dts: rockchip: Split rk3399-roc-pc for with and without mezzanine board.

From: "Heiko Stübner" <heiko@sntech.de>
To: Markus Reichl <m.reichl@fivetechno.de>,
	Jagan Teki <jagan@amarulasolutions.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Jagan Teki <jagan@amarulasolutions.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: Split rk3399-roc-pc for with and without mezzanine board.
Date: Mon, 04 Nov 2019 13:12:45 +0100	[thread overview]
Message-ID: <2226540.xovL9aYQn6@diego> (raw)
In-Reply-To: <075b3fa6-dab7-5fec-df68-b53f32bf061b@fivetechno.de>

Hi Markus,

Am Freitag, 1. November 2019, 17:54:23 CET schrieb Markus Reichl:
> For rk3399-roc-pc is a mezzanine board available that carries M.2 and
> POE interfaces. Use it with a separate dts.
> 
> Signed-off-by: Markus Reichl <m.reichl@fivetechno.de>
> ---
>  arch/arm64/boot/dts/rockchip/Makefile         |   1 +
>  .../boot/dts/rockchip/rk3399-roc-pc-mezz.dts  |  52 ++
>  .../arm64/boot/dts/rockchip/rk3399-roc-pc.dts | 757 +----------------
>  .../boot/dts/rockchip/rk3399-roc-pc.dtsi      | 767 ++++++++++++++++++
>  4 files changed, 821 insertions(+), 756 deletions(-)
>  create mode 100644 arch/arm64/boot/dts/rockchip/rk3399-roc-pc-mezz.dts
>  create mode 100644 arch/arm64/boot/dts/rockchip/rk3399-roc-pc.dtsi
> 
> diff --git a/arch/arm64/boot/dts/rockchip/Makefile b/arch/arm64/boot/dts/rockchip/Makefile
> index a959434ad46e..80ee9f1fc5f5 100644
> --- a/arch/arm64/boot/dts/rockchip/Makefile
> +++ b/arch/arm64/boot/dts/rockchip/Makefile
> @@ -28,6 +28,7 @@ dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-nanopi-neo4.dtb
>  dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-orangepi.dtb
>  dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-puma-haikou.dtb
>  dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-roc-pc.dtb
> +dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-roc-pc-mezz.dtb
>  dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-rock-pi-4.dtb
>  dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-rock960.dtb
>  dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3399-rockpro64.dtb
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-mezz.dts b/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-mezz.dts
> new file mode 100644
> index 000000000000..ee77677d2cf2
> --- /dev/null
> +++ b/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-mezz.dts
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright (c) 2017 T-Chip Intelligent Technology Co., Ltd
> + * Copyright (c) 2019 Markus Reichl <m.reichl@fivetechno.de>
> + */
> +
> +/dts-v1/;
> +#include "rk3399-roc-pc.dtsi"
> +
> +/ {
> +	model = "Firefly ROC-RK3399-PC Mezzanine Board";
> +	compatible = "firefly,roc-rk3399-pc", "rockchip,rk3399";

different board with same compatible isn't possible, so
you'll need a new compatible for it and add a new line to
the roc-pc entry in
	Documentation/devicetree/bindings/arm/rockchip.yaml

Either you see it as
- a board + hat, using dt overlay and same compatible
- a completely separate board, which needs a separate
  compatible as well

And as discussed in the previous thread
http://lists.infradead.org/pipermail/linux-rockchip/2019-November/027592.html
but also in Jagan's response that really is somehow a grey area
for something relatively static as the M.2 extension.

Heiko