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dmaengine: Add API to combine configuration and preparation (sg and single)

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Previously, configuration and preparation required two separate calls. This
works well when configuration is done only once during initialization.

However, in cases where the burst length or source/destination address must
be adjusted for each transfer, calling two functions is verbose and
requires additional locking to ensure both steps complete atomically.

Add a new API dmaengine_prep_config_single() and dmaengine_prep_config_sg()
and callback device_prep_config_sg() that combines configuration and
preparation into a single operation. If the configuration argument is
passed as NULL, fall back to the existing implementation.

Tested-by: Niklas Cassel <cassel@kernel.org>
Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260521-dma_prep_config-v7-1-1f73f4899883@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Frank Li
2026-06-30 16:42:30 +05:30
committed by Vinod Koul
parent dc59e4fea9
commit 796bdb33e8
2 changed files with 64 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Documentation/driver-api/dmaengine/client.rst
+9
View File
@@ -80,6 +80,10 @@ The details of these operations are:
- slave_sg: DMA a list of scatter gather buffers from/to a peripheral
- config_sg: Similar with slave_sg, just pass down dma_slave_config
struct to avoid calling dmaengine_slave_config() every time adjusting the
burst length or the FIFO address is needed.
- peripheral_dma_vec: DMA an array of scatter gather buffers from/to a
peripheral. Similar to slave_sg, but uses an array of dma_vec
structures instead of a scatterlist.
@@ -106,6 +110,11 @@ The details of these operations are:
unsigned int sg_len, enum dma_data_direction direction,
unsigned long flags);
struct dma_async_tx_descriptor *dmaengine_prep_config_sg(
struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction dir,
unsigned long flags, struct dma_slave_config *config);
struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec(
struct dma_chan *chan, const struct dma_vec *vecs,
size_t nents, enum dma_data_direction direction,
include/linux/dmaengine.h
+55 -8
View File
@@ -835,6 +835,7 @@ struct dma_filter {
* where the address and size of each segment is located in one entry of
* the dma_vec array.
* @device_prep_slave_sg: prepares a slave dma operation
* @device_prep_config_sg: prepares a slave DMA operation with dma_slave_config
* @device_prep_dma_cyclic: prepare a cyclic dma operation suitable for audio.
* The function takes a buffer of size buf_len. The callback function will
* be called after period_len bytes have been transferred.
@@ -934,6 +935,10 @@ struct dma_device {
struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction direction,
unsigned long flags, void *context);
struct dma_async_tx_descriptor *(*device_prep_config_sg)(
struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction direction,
unsigned long flags, struct dma_slave_config *config);
struct dma_async_tx_descriptor *(*device_prep_dma_cyclic)(
struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
size_t period_len, enum dma_transfer_direction direction,
@@ -974,22 +979,44 @@ static inline bool is_slave_direction(enum dma_transfer_direction direction)
(direction == DMA_DEV_TO_DEV);
}
static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single(
struct dma_chan *chan, dma_addr_t buf, size_t len,
enum dma_transfer_direction dir, unsigned long flags)
static inline struct dma_async_tx_descriptor *
dmaengine_prep_config_single(struct dma_chan *chan, dma_addr_t buf, size_t len,
enum dma_transfer_direction dir,
unsigned long flags,
struct dma_slave_config *config)
{
struct scatterlist sg;
if (!chan || !chan->device)
return NULL;
sg_init_table(&sg, 1);
sg_dma_address(&sg) = buf;
sg_dma_len(&sg) = len;
if (!chan || !chan->device || !chan->device->device_prep_slave_sg)
if (chan->device->device_prep_config_sg)
return chan->device->device_prep_config_sg(chan, &sg, 1, dir,
flags, config);
if (config)
if (dmaengine_slave_config(chan, config))
return NULL;
if (!chan->device->device_prep_slave_sg)
return NULL;
return chan->device->device_prep_slave_sg(chan, &sg, 1,
dir, flags, NULL);
}
static inline struct dma_async_tx_descriptor *
dmaengine_prep_slave_single(struct dma_chan *chan, dma_addr_t buf, size_t len,
enum dma_transfer_direction dir,
unsigned long flags)
{
return dmaengine_prep_config_single(chan, buf, len, dir, flags, NULL);
}
/**
* dmaengine_prep_peripheral_dma_vec() - Prepare a DMA scatter-gather descriptor
* @chan: The channel to be used for this descriptor
@@ -1010,17 +1037,37 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec(
dir, flags);
}
static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len,
enum dma_transfer_direction dir, unsigned long flags)
static inline struct dma_async_tx_descriptor *
dmaengine_prep_config_sg(struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction dir,
unsigned long flags, struct dma_slave_config *config)
{
if (!chan || !chan->device || !chan->device->device_prep_slave_sg)
if (!chan || !chan->device)
return NULL;
if (chan->device->device_prep_config_sg)
return chan->device->device_prep_config_sg(chan, sgl, sg_len,
dir, flags, config);
if (config)
if (dmaengine_slave_config(chan, config))
return NULL;
if (!chan->device->device_prep_slave_sg)
return NULL;
return chan->device->device_prep_slave_sg(chan, sgl, sg_len,
dir, flags, NULL);
}
static inline struct dma_async_tx_descriptor *
dmaengine_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction dir,
unsigned long flags)
{
return dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, NULL);
}
#ifdef CONFIG_RAPIDIO_DMA_ENGINE
struct rio_dma_ext;
static inline struct dma_async_tx_descriptor *dmaengine_prep_rio_sg(