async_tx: build-time toggling of async_{syndrome,xor}_val dma support

ioat3.2 does not support asynchronous error notifications which makes
the driver experience latencies when non-zero pq validate results are
expected.  Provide a mechanism for turning off async_xor_val and
async_syndrome_val via Kconfig.  This approach is generally useful for
any driver that specifies ASYNC_TX_DISABLE_CHANNEL_SWITCH and would like
to force the async_tx api to fall back to the synchronous path for
certain operations.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 5903a88351bf..b401dadad4a8 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -26,6 +26,8 @@ config INTEL_IOATDMA
         select DMA_ENGINE
         select DCA
         select ASYNC_TX_DISABLE_CHANNEL_SWITCH
+        select ASYNC_TX_DISABLE_PQ_VAL_DMA
+        select ASYNC_TX_DISABLE_XOR_VAL_DMA
         help
           Enable support for the Intel(R) I/OAT DMA engine present
           in recent Intel Xeon chipsets.