linux-kernel - Re: [PATCH V2 3/9] ARM: stm32: prepare stm32 family to welcome armv7 architecture

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Date:   Tue, 19 Dec 2017 15:38:38 +0100
From:   Alexandre Torgue <alexandre.torgue@...com>
To:     Arnd Bergmann <arnd@...db.de>, Ludovic Barre <ludovic.Barre@...com>
CC:     Russell King <linux@...linux.org.uk>,
        Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Gerald Baeza <gerald.baeza@...com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>
Subject: Re: [PATCH V2 3/9] ARM: stm32: prepare stm32 family to welcome armv7
 architecture



On 12/18/2017 09:24 PM, Arnd Bergmann wrote:
> On Mon, Dec 18, 2017 at 4:17 PM, Ludovic Barre <ludovic.Barre@...com> wrote:
>> From: Ludovic Barre <ludovic.barre@...com>
>>
>> This patch prepares the STM32 machine for the integration of Cortex-A
>> based microprocessor (MPU), on top of the existing Cortex-M
>> microcontroller family (MCU). Since both MCUs and MPUs are sharing
>> common hardware blocks we can keep using ARCH_STM32 flag for most of
>> them. If a hardware block is specific to one family we can use either
>> ARM_SINGLE_ARMV7M or ARCH_MULTI_V7 flag.
>>
>> Signed-off-by: Ludovic Barre <ludovic.barre@...com>
> 
> Looks good overall. Two more small comments:
> 
> 
>>
>> +if ARCH_STM32
>> +
>>   config MACH_STM32F429
>> -       bool "STMicrolectronics STM32F429"
>> -       depends on ARCH_STM32
>> +       bool "STMicroelectronics STM32F429"
>> +       depends on ARM_SINGLE_ARMV7M
>>          default y
> 
> Instead of the explicit dependency for each board, I'd leave the surrounding
> 'if ARM_SINGLE_ARMV7M'. I think you had in v1.
> 
>> diff --git a/arch/arm/mach-stm32/Makefile b/arch/arm/mach-stm32/Makefile
>> index bd0b7b5..5940af1 100644
>> --- a/arch/arm/mach-stm32/Makefile
>> +++ b/arch/arm/mach-stm32/Makefile
>> @@ -1 +1 @@
>> -obj-y += board-dt.o
>> +obj-$(CONFIG_ARM_SINGLE_ARMV7M) += board-mcu-dt.o
>> diff --git a/arch/arm/mach-stm32/board-dt.c b/arch/arm/mach-stm32/board-mcu-dt.c
>> similarity index 100%
>> rename from arch/arm/mach-stm32/board-dt.c
>> rename to arch/arm/mach-stm32/board-mcu-dt.c
> 
> Why the rename? I don't expect the new machines to have any notable
> contents in a board file, if any at all, so just use one file for both.
> I see the board-dt.c file refers to armv7m_restart, we can either put
> that in an #ifdef, or find a way to make it the default for all armv7-m
> platforms that don't provide any other restart method.
> 
Currently "restart" is not functional on stm32 MCU (at least for 
stm32f746, I will check on others MCU). My fear is if Ludovic made some 
patches to make "armv7m_restart" the default ".restart" function for all 
armv7-m platform, he will not be able to test it on stm32 MCU (as it is 
not currently working). I propose to do it in 2 steps:

1-Keep as you suggest only one board-dt.c file for both (MCU and MPU) 
and remove ".restart" function.

2-Investigate and send patches around ".restart" for both in an other 
series.

regards
Alex


>       Arnd
>