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>
diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c
index 79182dc..079ae8c 100644
--- a/crypto/async_tx/async_xor.c
+++ b/crypto/async_tx/async_xor.c
@@ -234,6 +234,17 @@
memcmp(a, a + 4, len - 4) == 0);
}
+static inline struct dma_chan *
+xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
+ struct page **src_list, int src_cnt, size_t len)
+{
+ #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
+ return NULL;
+ #endif
+ return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
+ src_cnt, len);
+}
+
/**
* async_xor_val - attempt a xor parity check with a dma engine.
* @dest: destination page used if the xor is performed synchronously
@@ -255,9 +266,7 @@
int src_cnt, size_t len, enum sum_check_flags *result,
struct async_submit_ctl *submit)
{
- struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR_VAL,
- &dest, 1, src_list,
- src_cnt, len);
+ struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
struct dma_device *device = chan ? chan->device : NULL;
struct dma_async_tx_descriptor *tx = NULL;
dma_addr_t *dma_src = NULL;