RE: [PATCH 05/18] ioat2+: add fence support

Sosnowski, Maciej
2009-09-15T16:07:07Z

Williams, Dan J wrote:
> In preparation for adding more operation types to the ioat3 path the
> driver needs to honor the DMA_PREP_FENCE flag. For example the async_tx api
> will hand xor->memcpy->xor chains to the driver with the 'fence' flag set on
> the first xor and the memcpy operation. This flag in turn sets the 'fence'
> flag in the descriptor control field telling the hardware that future
> descriptors in the chain depend on the result of the current descriptor, so
> wait for all writes to complete before starting the next operation.
>
> Note that ioat1 does not prefetch the descriptor chain, so does not
> require/support fenced operations.
>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>