On Mon, Jan 16, 2012 at 12:44 PM, Viresh Kumar [off-list ref] wrote:

On 1/16/2012 4:24 PM, Russell King - ARM Linux wrote:

quoted

Note that DMA engine drivers are not responsible for unmapping the buffers
when the transfer completes - that is the responsibility of the caller.

The automatic buffer unmapping is required for the async_tx APIs and
offload APIs.

In dw_dmac, it is only done for slave transfers. Is this Okay ??

Basically the driver using the dmaengine shall map/unmap buffers
used for slave transfers, not the driver.

I usually map them before setting up a transfer and unmaps them
when egtting the callback from the DMA engine that the transfer is
complete.

Why do you want to do this?

Yours,
Linus Walleij