From: Lior Amsalem <alior@xxxxxxxxxxx>
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@xxxxxxxxxxx>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
---
drivers/dma/mv_xor.c | 34 ++++++++++++++++++++++++++++++++++
drivers/dma/mv_xor.h | 11 ++++++-----
2 files changed, 40 insertions(+), 5 deletions(-)
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 @@ mv_xor_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
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 @@ static int mv_xor_channel_remove(struct mv_xor_chan *mv_chan)
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 @@ mv_xor_channel_add(struct mv_xor_device *xordev,
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 @@ mv_xor_channel_add(struct mv_xor_device *xordev,
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)) {
diff --git a/drivers/dma/mv_xor.h b/drivers/dma/mv_xor.h
index de40036..78edc7e 100644
--- a/drivers/dma/mv_xor.h
+++ b/drivers/dma/mv_xor.h
@@ -28,6 +28,9 @@
#define MV_XOR_THRESHOLD 1
#define MV_XOR_MAX_CHANNELS 2
+#define MV_XOR_MIN_BYTE_COUNT SZ_128
+#define MV_XOR_MAX_BYTE_COUNT (SZ_16M - 1)
+
/* Values for the XOR_CONFIG register */
#define XOR_OPERATION_MODE_XOR 0
#define XOR_OPERATION_MODE_MEMCPY 2
@@ -116,6 +119,9 @@ struct mv_xor_chan {
struct list_head all_slots;
int slots_allocated;
struct tasklet_struct irq_tasklet;
+ char dummy_src[MV_XOR_MIN_BYTE_COUNT];
+ char dummy_dst[MV_XOR_MIN_BYTE_COUNT];
+ dma_addr_t dummy_src_addr, dummy_dst_addr;
};
/**
@@ -184,9 +190,4 @@ struct mv_xor_desc {
#define mv_hw_desc_slot_idx(hw_desc, idx) \
((void *)(((unsigned long)hw_desc) + ((idx) << 5)))
-#define MV_XOR_MIN_BYTE_COUNT (128)
-#define XOR_MAX_BYTE_COUNT ((16 * 1024 * 1024) - 1)
-#define MV_XOR_MAX_BYTE_COUNT XOR_MAX_BYTE_COUNT
-
-
#endif
--
2.0.1
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