Re: [PATCH] ARM: make ARCH_S3C24XX select USE_OF and clean-up boot/dts/Makefile

From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: arm-soc <arm@kernel.org>, Olof Johansson <olof@lixom.net>,
	Arnd Bergmann <arnd@arndb.de>,
	devicetree@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] ARM: make ARCH_S3C24XX select USE_OF and clean-up boot/dts/Makefile
Date: Wed, 27 Dec 2017 11:00:18 +0900	[thread overview]
Message-ID: <CAK7LNAS_MYno9gwU5vy9dXYfj8mz8ost+BtN+c1CzW3jf2vmcA@mail.gmail.com> (raw)
In-Reply-To: <CAJKOXPfd+R0z-RcNLWn=rS6U0uBhDsZS8d-f-b4+jUeQBruc5Q@mail.gmail.com>

2017-12-26 2:39 GMT+09:00 Krzysztof Kozlowski <krzk@kernel.org>:
> On Sun, Dec 24, 2017 at 6:19 PM, Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
>> 2017-12-22 21:41 GMT+09:00 Krzysztof Kozlowski <krzk@kernel.org>:
>>> On Mon, Nov 27, 2017 at 3:19 AM, Masahiro Yamada
>>> <yamada.masahiro@socionext.com> wrote:
>>>> ARCH_S3C24XX is a very exceptional platform that some DT files in
>>>> arch/arm/boot/dts/, but does not select USE_OF.
>>>
>>> Not entirely. The platform does select USE_OF - when MACH_S3C2416_DT
>>> is chosen. For other boards USE_OF is not necessary because they do
>>> not use DT. Why you need to select it for entire arch?
>>>
>>> Best regards,
>>> Krzysztof
>>>
>>
>>
>> The reason is simple - to avoid compile error.
>>
>>
>> If I simply drop ifeq ($(CONFIG_OF),y)
>> but do not select ARCH_S3C24XX,
>> s3c2410_defconfig failed to build.
>>
>>
>> $ make -s ARCH=arm mrproper
>> $ make -s ARCH=arm s3c2410_defconfig
>> $ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-  dtbs
>>     ...
>>
>>   DTC     arch/arm/boot/dts/s3c2416-smdk2416.dtb
>> /bin/sh: 1: ./scripts/dtc/dtc: not found
>> scripts/Makefile.lib:310: recipe for target
>> 'arch/arm/boot/dts/s3c2416-smdk2416.dtb' failed
>> make[1]: *** [arch/arm/boot/dts/s3c2416-smdk2416.dtb] Error 127
>> arch/arm/Makefile:349: recipe for target 'dtbs' failed
>> make: *** [dtbs] Error 2
>>
>>
>> Another solution would be to enable dtb by CONFIG_MACH_S3C2416_DT.
>>
>>
>> diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
>> index d0381e9..950b5dd 100644
>> --- a/arch/arm/boot/dts/Makefile
>> +++ b/arch/arm/boot/dts/Makefile
>> @@ -800,7 +798,7 @@ dtb-$(CONFIG_ARCH_ROCKCHIP) += \
>>         rk3288-veyron-pinky.dtb \
>>         rk3288-veyron-speedy.dtb \
>>         rk3288-vyasa.dtb
>> -dtb-$(CONFIG_ARCH_S3C24XX) += \
>> +dtb-$(CONFIG_MACH_S3C2416_DT) += \
>>         s3c2416-smdk2416.dtb
>>  dtb-$(CONFIG_ARCH_S3C64XX) += \
>>         s3c6410-mini6410.dtb \
>>
>>
>>
>> If you migrate S3C24XX platform to DT,
>> per-board CONFIG option will go away.
>>
>> So, I think dtb-$(CONFIG_ARCH_S3C24XX) is OK.
>
> I think this second solution - using CONFIG_MACH_S3C2416_DT - makes
> more sense because:
> 1, S3C24xx will not be converted to DT. This is a legacy platform.
> 2. DT version supports only part of boards and peripherals so most of
> existing platforms will use non-DT boardfiles. Enabling OF on all of
> them is not useful for them.

I do not care this much.
I leave this up to you (and ARM-SOC maintainers).

> 3. The same error and solution probably applies to MACH_S3C64XX.

Maybe no.

Looking at arch/arm/mach-s3c64xx/Kconfig,
ARCH_S3C64XX depends on ARCH_MULTI_V6.

Multiplatform selects USE_OF.

>
> Best regards,
> Krzysztof
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-- 
Best Regards
Masahiro Yamada