[PATCH 3/3] ARM: Fix DMA-bounce code to allow sync from_device and to_device with bidirectional mappings.

[Simon Kågström]

On Sun, 23 Mar 2014 01:38:41 +0100
Krzysztof Halasa <khc at pm.waw.pl> wrote:

> This is equivalent of a more generic change to lib/dma-debug.c which is
> present since v2.6.33:
> 
> commit 42d53b4ff7d61487d18274ebdf1f70c1aef6f122
> dma-debug: allow DMA_BIDIRECTIONAL mappings to be synced with DMA_FROM_DEVICE
> and DMA_TO_DEVICE.
> 
> There is no need to perform full BIDIR sync (copying the buffers in case
> of swiotlb and similar schemes) if we know that the owner (CPU or device)
> hasn't altered the data.
> 
> Addresses the false-positive reported at
> http://bugzilla.kernel.org/show_bug.cgi?id=14169
> 
> Signed-off-by: Krzysztof Hałasa <khc at pm.waw.pl>

Tested-by: Simon Kagstrom <simon.kagstrom at netinsight.net>

(Tested with a e100 device which previously triggered this).

// Simon