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

[Markus Reichl]

Hi Jagan,

Am 18.11.19 um 12:44 schrieb Jagan Teki:
> On Mon, Nov 4, 2019 at 5:42 PM Heiko StÃbner <heiko@xxxxxxxxx> wrote:
>>
>> 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@xxxxxxxxxxxxx>
>> > ---
>> >  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@xxxxxxxxxxxxx>
>> > + */
>> > +
>> > +/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.
> 
> Sorry for late response on this. I still think that the "overlay would
> be a better suite" than having separate dts, since it is HAT which is
> optional to insert and have possibility of having another HAT if it
> really fit into it.
> 
> Comments?
Presently no other extension board does exist, I don't expect one.

I use it with rootfs on NVME on the mezzanine board.
It is convenient to have the NVME up before going to user space.

The board has SPI-NOR MTD storage to host U-Boot. 
In future U-Boot could boot from NVME directly without needing
an SD or MMC to host the boot kernel.

GruÃ,
-- 
Markus Reichl