From 47ec7f09bc107720905c96bc37771e4ed1ff0aed Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Wed, 13 May 2020 11:47:49 -0700 Subject: [PATCH] dmaengine: cookie bypass for out of order completion 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_COMPLETION_NO_ORDER DMA capability to allow the driver to flag the device's ability to complete operations out of order. Reported-by: Swathi Kovvuri Signed-off-by: Dave Jiang Tested-by: Swathi Kovvuri Link: https://lore.kernel.org/r/158939557151.20335.12404113976045569870.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul --- .../driver-api/dmaengine/provider.rst | 19 +++++++++++++++++++ drivers/dma/dmatest.c | 11 ++++++++++- drivers/dma/idxd/dma.c | 3 ++- include/linux/dmaengine.h | 2 ++ 4 files changed, 33 insertions(+), 2 deletions(-) diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index 56e5833e8a07b..ce68315482b1f 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -239,6 +239,22 @@ 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 does not support in order completion. + + - The driver should return DMA_OUT_OF_ORDER for device_tx_status if + the device is setting this capability. + + - All cookie tracking and checking API should be treated as invalid if + the device exports this capability. + + - At this point, this is incompatible with polling option for dmatest. + + - If this cap is set, the user is recommended to provide an unique + identifier for each descriptor sent to the DMA device in order to + properly track the completion. + These various types will also affect how the source and destination addresses change over time. @@ -399,6 +415,9 @@ 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 does not support in 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 b175229a4b01d..18f10154ba191 100644 --- a/drivers/dma/dmatest.c +++ b/drivers/dma/dmatest.c @@ -829,7 +829,10 @@ 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, @@ -1007,6 +1010,12 @@ static int dmatest_add_channel(struct dmatest_info *info, dtc->chan = chan; INIT_LIST_HEAD(&dtc->threads); + if (dma_has_cap(DMA_COMPLETION_NO_ORDER, dma_dev->cap_mask) && + info->params.polled) { + info->params.polled = false; + pr_warn("DMA_COMPLETION_NO_ORDER, polled disabled\n"); + } + if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask)) { if (dmatest == 0) { cnt = dmatest_add_threads(info, dtc, DMA_MEMCPY); diff --git a/drivers/dma/idxd/dma.c b/drivers/dma/idxd/dma.c index c64c1429d1606..0c892cbd72e01 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_COMPLETION_NO_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 e1c03339918f9..9f9a13a2c01f8 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, }; -- 2.30.2