Re: [PATCH] ata: libata depends on HAS_DMA

[Tejun Heo <htejun@gmail.com>]

Hello,

Arnd Bergmann wrote:
> On Friday 15 May 2009, Tejun Heo wrote:
>> FUJITA Tomonori wrote:
>>> Can libata call dma_supported() per device to decide DMA or PIO mode?
>>> Then, we can solve this problem by add dummy DMA API (just calls BUG)
>>> on such architectures, without Kconfig magic or adding ifdef (like the
>>> old ide stack does), I think.
> 
> That would be the !CONFIG_PCI half of the old
> include/asm-generic/dma-mapping.h file that you just removed,
> right?
> 
> In general, I'd prefer keeping the asm-generic/dma-mapping-broken.h
> implementation that gives us a compile-time error, but maybe there
> is an even better option based on the mn10300 implementation which
> basically pretends everything works with just page_to_phys() mappings.

Don't know much history here but I don't wanna sprinkle ifdefs around
in libata so I would much prefer dummy implementation which doesn't
fail compile.

>> Sure it can.  Which specific drivers are we talking about?
> 
> The main problem is libata-core.c, which references DMA mapping
> API calls that are only implemented on architectures setting
> CONFIG_HAS_DMA.

Yeah, sure, libata-core is used by every driver but I was wondering
whether only SFF drivers are of interest or there are others.

Thanks.

-- 
tejun