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SubjectRe: [PATCH 7/8] dmaengine/dw_dmac: Unmap all memory buffers after completion of slave transfers
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On Mon, Jan 16, 2012 at 12:44 PM, Viresh Kumar <viresh.kumar@st.com> wrote:
> On 1/16/2012 4:24 PM, Russell King - ARM Linux wrote:
>> 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


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