Messages in this thread Patch in this message |  | | From | Frank Li <> | | Date | Wed, 06 May 2026 16:44:13 -0400 | | Subject | [PATCH v4 1/9] 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> Signed-off-by: Frank Li <Frank.Li@nxp.com> --- change in v4 - drop context in device_prep_config_sg()
change in v3 - remove Deprecated for callback device_prep_slave_sg(). - Move condition check before sg init. - split function at return type. - move safe version to next patch
change in v2 - add () for function - use short name device_prep_sg(), remove "slave" and "config". the 'slave' is reduntant. after remove slave, the function name is difference existed one, so remove _config suffix. --- Documentation/driver-api/dmaengine/client.rst | 9 ++++ include/linux/dmaengine.h | 63 +++++++++++++++++++++++---- 2 files changed, 64 insertions(+), 8 deletions(-)
diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst index d491e385d61a98b8a804cd823caf254a2dc62cf4..5ee5d4a3596dd986b02f1bce3078ca6c4c1fb45a 100644 --- a/Documentation/driver-api/dmaengine/client.rst +++ b/Documentation/driver-api/dmaengine/client.rst @@ -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, diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index b3d251c9734e95e1b75cf6763d4d2c3a1c6a9910..defa377d2ef54d94e6337cdfa7826a091295535e 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -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( -- 2.43.0
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