RE: [GIT PULL] CMA and ARM DMA-mapping updates for v3.5

From: Marek Szyprowski
Date: Tue May 29 2012 - 10:50:47 EST


Hello,

On Tuesday, May 29, 2012 2:30 PM Russell King - ARM Linux wrote:

> I notice we have new warnings as a result of CMA being merged, though
> thankfully they're just in Kconfig:
>
> warning: (ARM) selects CMA which has unmet direct dependencies (HAVE_DMA_CONTIGUOUS &&
> HAVE_MEMBLOCK && EXPERIMENTAL)
>
> This seems totally weird: you're mandating that ARM must have CMA
> selected, but it's an experimental feature? So you're implying that
> the entire ARM kernel becomes totally experimental for the next
> release cycle?
>
> I think this needs fixing.

No, that wasn't my intention. I will provide a patch which removes unconditional dependency
on CMA - it will let one to disable CMA and use old allocation method if needed, but this
requires a few more changes in the dma-mapping implementation. I wasn't aware of the
consequences and no one has complained about this since v15 of CMA patches (Aug 2011).

Best regards
--
Marek Szyprowski
Samsung Poland R&D Center


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