The cookie tracking in dmaengine expects all submissions completed in
order. Some DMA devices like Intel DSA can complete submissions out of
order, especially if configured with a work queue sharing multiple DMA
engines. Add a status DMA_OUT_OF_ORDER that tx_status can be returned for
those DMA devices. The user should use callbacks to track the completion
rather than the DMA cookie. This would address the issue of dmatest
complaining that descriptors are "busy" when the cookie count goes
backwards due to out of order completion. Add DMA_NO_COMPLETION_ORDER
DMA capability to allow the driver to flag the device's ability to complete
operations out of order.
Reported-by: Swathi Kovvuri <swathi.kovvuri@xxxxxxxxx>
Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Tested-by: Swathi Kovvuri <swathi.kovvuri@xxxxxxxxx>
---
v2:
- Add DMA capability (vinod)
- Add documentation (vinod)
Documentation/driver-api/dmaengine/provider.rst | 11 +++++++++++
drivers/dma/dmatest.c | 5 ++++-
drivers/dma/idxd/dma.c | 3 ++-
include/linux/dmaengine.h | 2 ++
4 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
index 56e5833e8a07..783ca141e147 100644
--- a/Documentation/driver-api/dmaengine/provider.rst
+++ b/Documentation/driver-api/dmaengine/provider.rst
@@ -239,6 +239,14 @@ Currently, the types available are:
want to transfer a portion of uncompressed data directly to the
display to print it
+- DMA_COMPLETION_NO_ORDER
+
+ - The device supports out of order completion of the operations.
+
+ - The driver should return DMA_OUT_OF_ORDER for device_tx_status if
+ the device supports out of order completion and the completion is
+ is expected to be completed out of order.
+
These various types will also affect how the source and destination
addresses change over time.
@@ -399,6 +407,9 @@ supported.
- In the case of a cyclic transfer, it should only take into
account the current period.
+ - Should return DMA_OUT_OF_ORDER if the device supports out of order
+ completion and is completing the operation out of order.
+
- This function can be called in an interrupt context.
- device_config
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index a2cadfa2e6d7..8953e096a05c 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -821,7 +821,10 @@ static int dmatest_func(void *data)
result("test timed out", total_tests, src->off, dst->off,
len, 0);
goto error_unmap_continue;
- } else if (status != DMA_COMPLETE) {
+ } else if (status != DMA_COMPLETE &&
+ !(dma_has_cap(DMA_COMPLETION_NO_ORDER,
+ dev->cap_mask) &&
+ status == DMA_OUT_OF_ORDER)) {
result(status == DMA_ERROR ?
"completion error status" :
"completion busy status", total_tests, src->off,
diff --git a/drivers/dma/idxd/dma.c b/drivers/dma/idxd/dma.c
index c64c1429d160..8cce6de26116 100644
--- a/drivers/dma/idxd/dma.c
+++ b/drivers/dma/idxd/dma.c
@@ -133,7 +133,7 @@ static enum dma_status idxd_dma_tx_status(struct dma_chan *dma_chan,
dma_cookie_t cookie,
struct dma_tx_state *txstate)
{
- return dma_cookie_status(dma_chan, cookie, txstate);
+ return DMA_OUT_OF_ORDER;
}
/*
@@ -174,6 +174,7 @@ int idxd_register_dma_device(struct idxd_device *idxd)
INIT_LIST_HEAD(&dma->channels);
dma->dev = &idxd->pdev->dev;
+ dma_cap_set(DMA_NO_COMPLETION_ORDER, dma->cap_mask);
dma->device_release = idxd_dma_release;
if (idxd->hw.opcap.bits[0] & IDXD_OPCAP_MEMMOVE) {
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 21065c04c4ac..1123f4d15bae 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -39,6 +39,7 @@ enum dma_status {
DMA_IN_PROGRESS,
DMA_PAUSED,
DMA_ERROR,
+ DMA_OUT_OF_ORDER,
};
/**
@@ -61,6 +62,7 @@ enum dma_transaction_type {
DMA_SLAVE,
DMA_CYCLIC,
DMA_INTERLEAVE,
+ DMA_COMPLETION_NO_ORDER,
/* last transaction type for creation of the capabilities mask */
DMA_TX_TYPE_END,
};
