Re: [PATCH 4/4] arm64: dts: imx8mm-kontron: Add DL (Display-Line) overlay with LVDS support

[Frieder Schrempf <frieder.schrempf@kontron.de>]

On 28.08.24 9:27 AM, Frieder Schrempf wrote:
> Hi Shawn,
> 
> On 28.08.24 4:56 AM, Shawn Guo wrote:
>> On Tue, Aug 06, 2024 at 03:33:02PM +0200, Frieder Schrempf wrote:
>>> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>>>
>>> The Kontron Electronics DL i.MX8MM consists of the BL i.MX8MM board
>>> and a 7" LVDS panel. Provide an overlay that enables the panel.
>>>
>>> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
>>> ---
>>> Note: This currently throws the following warnings:
>>>
>>> Warning (graph_port): /fragment@3: graph port node name should be 'port'
>>> Warning (graph_endpoint): /fragment@3/__overlay__: graph endpoint node name should be 'endpoint'
>>> Warning (graph_endpoint): /fragment@3/__overlay__: graph connection to node '/fragment@7/__overlay__/ports/port@0/endpoint' is not bidirectional
>>>
>>> There is the following commit in DTC that relaxes these checks and
>>> will eventually resolve these warnings:
>>>
>>> 84b056a89d ("checks: relax graph checks for overlays")
>>>
>>> https://git.kernel.org/pub/scm/utils/dtc/dtc.git/commit/?id=84b056a89d3c5b6cf6c5eeeafd4c4b14d6333aa9
>>> ---
>>>  arch/arm64/boot/dts/freescale/Makefile        |   4 +
>>>  .../boot/dts/freescale/imx8mm-kontron-dl.dtso | 210 ++++++++++++++++++
>>>  2 files changed, 214 insertions(+)
>>>  create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-kontron-dl.dtso
>>>
>>> diff --git a/arch/arm64/boot/dts/freescale/Makefile b/arch/arm64/boot/dts/freescale/Makefile
>>> index f04c22b7de72e..d8af069139920 100644
>>> --- a/arch/arm64/boot/dts/freescale/Makefile
>>> +++ b/arch/arm64/boot/dts/freescale/Makefile
>>> @@ -244,6 +244,10 @@ dtb-$(CONFIG_ARCH_MXC) += imx93-tqma9352-mba93xxla.dtb
>>>  dtb-$(CONFIG_ARCH_MXC) += imx93-var-som-symphony.dtb
>>>  dtb-$(CONFIG_ARCH_MXC) += imx95-19x19-evk.dtb
>>>  
>>> +imx8mm-kontron-dl-dtbs			:= imx8mm-kontron-bl.dtb imx8mm-kontron-dl.dtbo
>>> +
>>> +dtb-$(CONFIG_ARCH_MXC) += imx8mm-kontron-dl.dtb
>>> +
>>>  imx8mm-venice-gw72xx-0x-imx219-dtbs	:= imx8mm-venice-gw72xx-0x.dtb imx8mm-venice-gw72xx-0x-imx219.dtbo
>>>  imx8mm-venice-gw72xx-0x-rpidsi-dtbs	:= imx8mm-venice-gw72xx-0x.dtb imx8mm-venice-gw72xx-0x-rpidsi.dtbo
>>>  imx8mm-venice-gw72xx-0x-rs232-rts-dtbs	:= imx8mm-venice-gw72xx-0x.dtb imx8mm-venice-gw72xx-0x-rs232-rts.dtbo
>>> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-kontron-dl.dtso b/arch/arm64/boot/dts/freescale/imx8mm-kontron-dl.dtso
>>> new file mode 100644
>>> index 0000000000000..b2d593d700e2d
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/freescale/imx8mm-kontron-dl.dtso
>>> @@ -0,0 +1,210 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Copyright (C) 2023 Kontron Electronics GmbH
>>
>> 2024?
>>
>>> + */
>>> +
>>> +/dts-v1/;
>>> +/plugin/;
>>> +
>>> +#include <dt-bindings/gpio/gpio.h>
>>> +#include "imx8mm-pinfunc.h"
>>> +
>>> +&{/} {
>>> +	compatible = "kontron,imx8mm-bl", "kontron,imx8mm-sl", "fsl,imx8mm";
>>
>> Not sure we need compatible in overlay.
> 
> I've seen discussions around this elsewhere. We don't need it, but it
> seems a nice way to express which base DT this overlay is intended to be
> applied to.
> 
> Anyway, I can remove the compatible for now. Your other comments will be
> fixed in v2 as well.

For whatever reasons, the build for the combined DT + overlay works only
if the compatible is in place. Therefore I will keep it.

DTC_FLAGS=-@ make ARCH=arm64 CHECK_DTBS=y
CROSS_COMPILE=aarch64-linux-gnu- -j16 freescale/imx8mm-kontron-dl.dtb

  DTOVLCH arch/arm64/boot/dts/freescale/imx8mm-kontron-dl.dtb

Failed to apply 'arch/arm64/boot/dts/freescale/imx8mm-kontron-dl.dtbo':
FDT_ERR_NOTFOUND