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

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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>
This commit is contained in:
Dan Williams
2009-11-19 17:10:37 -07:00
parent 4499a24dec
commit 7b3cc2b1fc
6 changed files with 46 additions and 6 deletions
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15
crypto/async_tx/async_xor.c
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@@ -234,6 +234,17 @@ static int page_is_zero(struct page *p, unsigned int offset, size_t len)
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 @@ async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
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;