[PATCH 2/3] arm: caches: add DCACHE_DEFAULT_OPTION

[Marek Vasut]

On 4/9/20 8:06 PM, Patrick DELAUNAY wrote:
> Dear Marek,

Hi,

>> Sent: jeudi 9 avril 2020 12:21
>> To: Patrick DELAUNAY <patrick.delaunay at st.com>; u-boot at lists.denx.de
>>
>> On 4/9/20 12:01 PM, Patrick DELAUNAY wrote:
>>> Dear Marek,
>>
>> Hi,
>>
>>>> From: Uboot-stm32 <uboot-stm32-bounces at st-md-mailman.stormreply.com>
>>>> On Behalf Of Patrick DELAUNAY
>>>>
>>>> Dear Marek,
>>>>
>>>>> From: Marek Vasut <marex at denx.de>
>>>>> Sent: vendredi 3 avril 2020 23:29
>>>>>
>>>>> On 4/3/20 10:28 AM, Patrick Delaunay wrote:
>>>>>> Add the new flags DCACHE_DEFAULT_OPTION to define the default
>>>>>> option to use according the compilation flags
>>>>>> CONFIG_SYS_ARM_CACHE_WRITETHROUGH or
>>>>> CONFIG_SYS_ARM_CACHE_WRITEALLOC.
>>>>>
>>>>> Can't you unify these macros into a single Kconfig "select"
>>>>> statement instead , and then just select the matching cache configuration in
>> Kconfig ?
>>>>
>>>> Yes I will try, with 2 steps
>>>> - migrate existing CONFIG_SYS_ARM_CACHE_.... in Kconfig
>>>
>>> First step done...
>>> I will push it as a separate patchset I think.
>>>
>>>> - add new option CONFIG_SYS_ARM_CACHE_OPTION
>>>
>>> In fact it is to difficult to use select because each defines
>>> DCACHE_XXX value can have several values
>>>
>>> they are build according CONFIG_ARM64 / LPAE
>>>
>>> But, I can't use this define in Kconfig
>>>
>>> I try :
>>> option	ARM_OPTION
>>> 	int "option"
>>> 	default DCACHE_WRITETHROUGHT if
>> CONFIG_SYS_ARM_CACHE_WRITETHROUGH
>>> 	default DCACHE_ WRITEALLOC if CONFIG_SYS_ARM_CACHE_
>> WRITEALLOC
>>> 	default DCACHE_WRITEBACK if
>> CONFIG_SYS_ARM_CACHE_WRITEBACK
>>>
>>> int and hex is invalid, and string can't be use with "".
>>>
>>> And I don't found way to build it automatically when option is activated.
>>>
>>> Any idea ?
>>
>> Maybe you can have a select in the Kconfig to set some differently named option,
>> e.g.
>>
>> DCACHE_MODE_WRITE{THROUGH,ALLOC,BACK}
>>
>> and then an ifdef in some header file, e.g.
>>
>> #ifdef CONFIG_DCACHE_MODE_WRITETHROUGH
>> #define ARM_CACHE_MODE DCACHE_WRITETHROUGH ...
>>
>> And then use ARM_CACHE_MODE where you need a value and
>> CONFIG_DCACHE_MODE{...} where you need a config option check.
>>
>> Does this work ?
> 
> I try with string and default (as select is allowed on for bolean or trisate),
> And I failed :-<
> 
> I don't found a way to have the de-stringficate the KConfig option
> to generated the correct define

The result is a boolean , isn't it ? One out of N configs ends up being
defined and the rest are not defined.

> config SYS_ARM_CACHE_POLICY
> 	string "Name of the ARM data write cache policy"
> 	default WRITEBACK if SYS_ARM_CACHE_WRITEBACK
> 	default WRITETHROUGH if SYS_ARM_CACHE_WRITEBACK
> 	default WRITEALLOC if SYS_ARM_CACHE_WRITEALLOC
> 
> #define DCACHE_DEFAULT_OPTION	DCACHE_ ## CONFIG_SYS_ARM_CACHE_POLICY
> 
> => error: ‘DCACHE_CONFIG_SYS_ARM_CACHE_POLICY’ undeclared (first use in this function); did you mean ‘CONFIG_SYS_ARM_CACHE_POLICY’?
> 
> #define DCACHE_OPTION(s)	DCACHE_ ## CONFIG_SYS_ARM_CACHE_POLICY
> 
> #define DCACHE_DEFAULT_OPTION	DCACHE_OPTION(CONFIG_SYS_ARM_CACHE_POLICY)
> 
> arch/arm/include/asm/system.h:488:26: error: ‘DCACHE_’ undeclared (first use in this function); did you mean ‘DCACHE_OFF’?
> arch/arm/lib/cache-cp15.c:99:25: error: expected ‘)’ before string constant
> 
> The stringification is possible but not the inverse operation (remove the quote)...
> 
> In my .config, CONFIG_SYS_ARM_CACHE_POLICY="WRITEBACK"

What about this:

choice
prompt "Cache policy"
 default CACHE_WRITEBACK

config CACHE_WRITEBACK
 bool "Writeback"

config ...

endchoice

and then in some header

#ifdef CONFIG_CACHE_WRITEBACK
#define CONFIF_SYS_ARM_CACHE_WRITEBACK
#else
...

Would that work ?

But I feel I might really be missing the question here.