dma: mv_xor: Add support for DMA_INTERRUPT
The driver is capable of supporting DMA_INTERRUPT by issuing a dummy 128-byte
transfer. This helps removing a poll in the async_tx stack, replacing it with
a completion interrupt.
Signed-off-by: Lior Amsalem <alior@marvell.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
index 744a007..769d35c 100644
--- a/drivers/dma/mv_xor.c
+++ b/drivers/dma/mv_xor.c
@@ -538,6 +538,24 @@
return mv_xor_prep_dma_xor(chan, dest, &src, 1, len, flags);
}
+static struct dma_async_tx_descriptor *
+mv_xor_prep_dma_interrupt(struct dma_chan *chan, unsigned long flags)
+{
+ struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
+ dma_addr_t src, dest;
+ size_t len;
+
+ src = mv_chan->dummy_src_addr;
+ dest = mv_chan->dummy_dst_addr;
+ len = MV_XOR_MIN_BYTE_COUNT;
+
+ /*
+ * We implement the DMA_INTERRUPT operation as a minimum sized
+ * XOR operation with a single dummy source address.
+ */
+ return mv_xor_prep_dma_xor(chan, dest, &src, 1, len, flags);
+}
+
static void mv_xor_free_chan_resources(struct dma_chan *chan)
{
struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
@@ -881,6 +899,10 @@
dma_free_coherent(dev, MV_XOR_POOL_SIZE,
mv_chan->dma_desc_pool_virt, mv_chan->dma_desc_pool);
+ dma_unmap_single(dev, mv_chan->dummy_src_addr,
+ MV_XOR_MIN_BYTE_COUNT, DMA_FROM_DEVICE);
+ dma_unmap_single(dev, mv_chan->dummy_dst_addr,
+ MV_XOR_MIN_BYTE_COUNT, DMA_TO_DEVICE);
list_for_each_entry_safe(chan, _chan, &mv_chan->dmadev.channels,
device_node) {
@@ -910,6 +932,16 @@
dma_dev = &mv_chan->dmadev;
+ /*
+ * These source and destination dummy buffers are used to implement
+ * a DMA_INTERRUPT operation as a minimum-sized XOR operation.
+ * Hence, we only need to map the buffers at initialization-time.
+ */
+ mv_chan->dummy_src_addr = dma_map_single(dma_dev->dev,
+ mv_chan->dummy_src, MV_XOR_MIN_BYTE_COUNT, DMA_FROM_DEVICE);
+ mv_chan->dummy_dst_addr = dma_map_single(dma_dev->dev,
+ mv_chan->dummy_dst, MV_XOR_MIN_BYTE_COUNT, DMA_TO_DEVICE);
+
/* allocate coherent memory for hardware descriptors
* note: writecombine gives slightly better performance, but
* requires that we explicitly flush the writes
@@ -934,6 +966,8 @@
dma_dev->dev = &pdev->dev;
/* set prep routines based on capability */
+ if (dma_has_cap(DMA_INTERRUPT, dma_dev->cap_mask))
+ dma_dev->device_prep_dma_interrupt = mv_xor_prep_dma_interrupt;
if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask))
dma_dev->device_prep_dma_memcpy = mv_xor_prep_dma_memcpy;
if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {