Re: [PATCH v2] mtd: onenand: omap2: Disable DMA for HIGHMEM buffers

From: Boris Brezillon
Date: Fri Apr 20 2018 - 16:01:48 EST


Hi Ladislav,

On Mon, 16 Apr 2018 08:52:59 +0200
Ladislav Michl <ladis@xxxxxxxxxxxxxx> wrote:

> dma_map_single doesn't get the proper DMA address for vmalloced area,

That's not true, it returns the right DMA (physical) address, it's just
that:

1/ the memory location is not necessarily physically contiguous
2/ in case your arch is VIVT ot VIPT, there may be several entries in
the cache pointing to the same physical location, and the cache
maintenance operations done by dma_map_single() will only operate on
one of these entries.

> so disable DMA in this case.
>

The fix looks good though. Can you rephrase your commit message to make
it clearer.

Thanks,

Boris