Re: [PATCH] drivers: Let several drivers depends on HAS_IOMEM for 'devm_ioremap_resource'

Chen Gang
2014-07-17T09:29:31Z

On 07/17/2014 05:20 PM, Arnd Bergmann wrote:
> On Thursday 17 July 2014 09:27:58 Chen Gang wrote:
>> gfp_t gfp_mask, unsigned int order);
>> extern void devm_free_pages(struct device *dev, unsigned long addr);
>>
>> +#ifdef CONFIG_HAS_IOMEM
>> void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
>> +#elif defined(CONFIG_COMPILE_TEST)
>> +static inline void __iomem *devm_ioremap_resource(struct device *dev,
>> + struct resource *res)
>> +{
>> + pr_warn("no hardware io memory, only for COMPILE_TEST\n");
>> + return (__force void __iomem *)ERR_PTR(-ENXIO);
>> +}
>> +#endif /* CONFIG_HAS_IOMEM || CONFIG_COMPILE_TEST */
>>
>> /* allows to add/remove a custom action to devres stack */
>
> To be honest, I think it's a bad idea to introduce wrappers functions
> that are only available when CONFIG_COMPILE_TEST is set.
>
> COMPILE_TEST is a great tool in general, but it has its limits.
> In particular, the case for !CONFIG_IOMEM is completely obscure
> and we won't find any bugs by allowing more drivers to be built
> in those configurations, but attempting to do it would cause
> endless churn by changing each instance of 'depends on HAS_IOMEM'
> to 'depends on HAS_IOMEM || COMPILE_TEST'.
>

Architecture members and driver members really have different tastes,
they are different roles. It really need additional discussion.

For me, I only want to change devm_io*map*, not touch so much.

Welcome any other members' idea or suggestions.

> Note that s390 no has gained support for IOMEM, tile has it most
> of the time (when PCI is enabled, so you get it in half the
> test builds already), score should set HAS_IOMEM and doesn't
> even have public compilers, and uml doesn't even compile in
> latest mainline. Nothing else ever sets NO_IOMEM.
>

In latest gcc and binutils, can compile score cross compiler
successfully for building kernel (but I am not quite sure whether the
compiling result are really OK, but I guess so).

And next (maybe after finish allmodconfig for microblaze), I shall try
to let uml pass allmodconfig for linux-next tree.

Thanks.
--
Chen Gang

Open, share, and attitude like air, water, and life which God blessed