dmaengine: xgene-dma: Remove memcpy offload support due to performance drop
The DMA engine supports memory copy, RAID5 XOR, RAID6 PQ, and other
computations. But the bandwidth of the entire DMA engine is shared
among all channels. This patch re-configures operations availability
such that one can achieve maximum performance for XOR and PQ
computation by removing the memory offload operations.
Signed-off-by: Rameshwar Prasad Sahu <rsahu@apm.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/xgene-dma.c b/drivers/dma/xgene-dma.c
index dc84ed1..ecc9e90 100644
--- a/drivers/dma/xgene-dma.c
+++ b/drivers/dma/xgene-dma.c
@@ -907,60 +907,6 @@
chan->desc_pool = NULL;
}
-static struct dma_async_tx_descriptor *xgene_dma_prep_memcpy(
- struct dma_chan *dchan, dma_addr_t dst, dma_addr_t src,
- size_t len, unsigned long flags)
-{
- struct xgene_dma_desc_sw *first = NULL, *new;
- struct xgene_dma_chan *chan;
- size_t copy;
-
- if (unlikely(!dchan || !len))
- return NULL;
-
- chan = to_dma_chan(dchan);
-
- do {
- /* Allocate the link descriptor from DMA pool */
- new = xgene_dma_alloc_descriptor(chan);
- if (!new)
- goto fail;
-
- /* Create the largest transaction possible */
- copy = min_t(size_t, len, XGENE_DMA_MAX_64B_DESC_BYTE_CNT);
-
- /* Prepare DMA descriptor */
- xgene_dma_prep_cpy_desc(chan, new, dst, src, copy);
-
- if (!first)
- first = new;
-
- new->tx.cookie = 0;
- async_tx_ack(&new->tx);
-
- /* Update metadata */
- len -= copy;
- dst += copy;
- src += copy;
-
- /* Insert the link descriptor to the LD ring */
- list_add_tail(&new->node, &first->tx_list);
- } while (len);
-
- new->tx.flags = flags; /* client is in control of this ack */
- new->tx.cookie = -EBUSY;
- list_splice(&first->tx_list, &new->tx_list);
-
- return &new->tx;
-
-fail:
- if (!first)
- return NULL;
-
- xgene_dma_free_desc_list(chan, &first->tx_list);
- return NULL;
-}
-
static struct dma_async_tx_descriptor *xgene_dma_prep_sg(
struct dma_chan *dchan, struct scatterlist *dst_sg,
u32 dst_nents, struct scatterlist *src_sg,
@@ -1717,7 +1663,6 @@
dma_cap_zero(dma_dev->cap_mask);
/* Set DMA device capability */
- dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
dma_cap_set(DMA_SG, dma_dev->cap_mask);
/* Basically here, the X-Gene SoC DMA engine channel 0 supports XOR
@@ -1744,7 +1689,6 @@
dma_dev->device_free_chan_resources = xgene_dma_free_chan_resources;
dma_dev->device_issue_pending = xgene_dma_issue_pending;
dma_dev->device_tx_status = xgene_dma_tx_status;
- dma_dev->device_prep_dma_memcpy = xgene_dma_prep_memcpy;
dma_dev->device_prep_dma_sg = xgene_dma_prep_sg;
if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
@@ -1797,8 +1741,7 @@
/* DMA capability info */
dev_info(pdma->dev,
- "%s: CAPABILITY ( %s%s%s%s)\n", dma_chan_name(&chan->dma_chan),
- dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask) ? "MEMCPY " : "",
+ "%s: CAPABILITY ( %s%s%s)\n", dma_chan_name(&chan->dma_chan),
dma_has_cap(DMA_SG, dma_dev->cap_mask) ? "SGCPY " : "",
dma_has_cap(DMA_XOR, dma_dev->cap_mask) ? "XOR " : "",
dma_has_cap(DMA_PQ, dma_dev->cap_mask) ? "PQ " : "");