Hi Marek,
On Tuesday 16 August 2011 07:35:05 Marek Szyprowski wrote:
> On Friday, August 12, 2011 11:55 PM Laurent Pinchart wrote:
> > On Wednesday 10 August 2011 10:23:37 Marek Szyprowski wrote:
> > > From: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
> > >
> > > Scatter-gather lib provides a helper functions to allocate scatter
> > > list, so there is no need to use vmalloc for it. sg_alloc_table()
> > > splits allocation into page size chunks and links them together into a
> > > chain.
> >
> > Last time I check ARM platforms didn't support SG list chaining. Has that
> > been fixed ?
>
> DMA-mapping code for ARM platform use for_each_sg() macro which has no
> problems with chained SG lists.
for_each_sg() is fine, but sg_alloc_table() doesn't seem to be.
__sg_alloc_table(), called from sg_alloc_table(), starts with
#ifndef ARCH_HAS_SG_CHAIN
BUG_ON(nents > max_ents);
#endif
It also calls sg_chain() internally, which starts with
#ifndef ARCH_HAS_SG_CHAIN
BUG();
#endif
ARCH_HAS_SG_CHAIN is defined on ARM if CONFIG_ARM_HAS_SG_CHAIN is set. That's
a boolean Kconfig option that is currently never set.
--
Regards,
Laurent Pinchart
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