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

On Mon, Nov 18, 2019 at 5:31 PM Heiko Stübner [off-list ref] wrote:

Am Montag, 18. November 2019, 12:57:16 CET schrieb Markus Reichl:

quoted

Hi Jagan,

Am 18.11.19 um 12:44 schrieb Jagan Teki:

quoted

On Mon, Nov 4, 2019 at 5:42 PM Heiko Stübner [off-list ref] wrote:

quoted

Hi Markus,

Am Freitag, 1. November 2019, 17:54:23 CET schrieb Markus Reichl:

quoted

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 <redacted>
---
 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.

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.

And that is exactly the reason while I think it's sane to have this
as a separate board. For more common hats with random
extended functionality this might be different.

But people attaching the nvme-"hat" will in most all cases do so quite
permanently as well ;-) .

I did understand this completely and I do agree this point and use-case.

But what if we have overlay, and give tendency to use it at bootloader
level for nvme-"hat" so it can satisfy both common and random HAT
functionalities.

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