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

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Date:   Thu, 21 Dec 2017 17:39:39 +0100
From:   Ludovic BARRE <ludovic.barre@...com>
To:     Alexandre Torgue <alexandre.torgue@...com>,
        Arnd Bergmann <arnd@...db.de>
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

hi Arnd

just a ping, on Alex's proposal (below) about armv7m_restart
(Currently "restart" is not functional on stm32 MCU).

BR
Ludo
On 12/19/2017 03:38 PM, Alexandre Torgue wrote:
> 
> 
> 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.

I resend

> 
> regards
> Alex
> 
> 
>>       Arnd
>>