From 796bdb33e86aec8504bf8868e0665f120638ac72 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:47 -0400 Subject: [PATCH 1/9] dmaengine: Add API to combine configuration and preparation (sg and single) 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 Acked-by: Manivannan Sadhasivam Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-1-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- 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 d491e385d61a..5ee5d4a3596d 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 b3d251c9734e..defa377d2ef5 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( From af900b7dc1e1cdac571ac38e7fee80f1a1776a62 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:48 -0400 Subject: [PATCH 2/9] dmaengine: Add safe API to combine configuration and preparation Introduce dmaengine_prep_config_single_safe() and dmaengine_prep_config_sg_safe() to provide a reentrant-safe way to combine slave configuration and transfer preparation. Drivers may implement the new device_prep_config_sg() callback to perform both steps atomically. If the callback is not provided, the helpers fall back to calling dmaengine_slave_config() followed by dmaengine_prep_slave_sg() under per-channel spinlock protection. Tested-by: Niklas Cassel Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-2-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/dma/dmaengine.c | 2 + include/linux/dmaengine.h | 86 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 88 insertions(+) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 9049171df857..23e3bb18c166 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -1100,6 +1100,8 @@ static int __dma_async_device_channel_register(struct dma_device *device, chan->dev->device.parent = device->dev; chan->dev->chan = chan; chan->dev->dev_id = device->dev_id; + spin_lock_init(&chan->lock); + if (!name) dev_set_name(&chan->dev->device, "dma%dchan%d", device->dev_id, chan->chan_id); else diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index defa377d2ef5..6fe46c0c9452 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -322,6 +322,8 @@ struct dma_router { * @slave: ptr to the device using this channel * @cookie: last cookie value returned to client * @completed_cookie: last completed cookie for this channel + * @lock: protect between config and prepare transfer when driver have not + * implemented callback device_prep_config_sg(). * @chan_id: channel ID for sysfs * @dev: class device for sysfs * @name: backlink name for sysfs @@ -341,6 +343,12 @@ struct dma_chan { dma_cookie_t cookie; dma_cookie_t completed_cookie; + /* + * protect between config and prepare transfer because *_prep() may be + * called from complete callback, which is in GFP_NOSLEEP context. + */ + spinlock_t lock; + /* sysfs */ int chan_id; struct dma_chan_dev *dev; @@ -1068,6 +1076,84 @@ dmaengine_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, return dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, NULL); } +/** + * dmaengine_prep_config_sg_safe - prepare a scatter-gather DMA transfer + * with atomic slave configuration update + * @chan: DMA channel + * @sgl: scatterlist for the transfer + * @sg_len: number of entries in @sgl + * @dir: DMA transfer direction + * @flags: transfer preparation flags + * @config: DMA slave configuration for this transfer + * + * Prepare a DMA scatter-gather transfer together with a corresponding slave + * configuration update in a re-entrant and race-safe manner. + * + * DMA engine drivers may implement the optional + * device_prep_config_sg() callback to perform both the slave configuration + * and descriptor preparation atomically. In this case, the operation is + * fully handled by the DMA engine driver. + * + * If the DMA engine driver does not implement device_prep_config_sg(), falls + * back to calling dmaengine_slave_config() followed by dmaengine_prep_slave_sg(). + * The fallback path is protected by a per-channel spinlock to ensure that + * concurrent callers cannot interleave configuration and descriptor preparation + * on the same DMA channel. + * + * Return: Pointer to a prepared DMA async transaction descriptor on success, + * or %NULL if the transfer could not be prepared. + */ +static inline struct dma_async_tx_descriptor * +dmaengine_prep_config_sg_safe(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 *tx; + unsigned long spinlock_flags; + + if (!chan || !chan->device) + return NULL; + + if (!chan->device->device_prep_config_sg) + spin_lock_irqsave(&chan->lock, spinlock_flags); + + tx = dmaengine_prep_config_sg(chan, sgl, sg_len, dir, flags, config); + + if (!chan->device->device_prep_config_sg) + spin_unlock_irqrestore(&chan->lock, spinlock_flags); + + return tx; +} + +/** + * dmaengine_prep_config_single_safe - prepare a single-buffer DMA transfer + * with atomic slave configuration update + * @chan: DMA channel + * @buf: DMA buffer address + * @len: length of the transfer in bytes + * @dir: DMA transfer direction + * @flags: transfer preparation flags + * @config: DMA slave configuration for this transfer + * + * Detail see dmaengine_prep_config_sg_safe(). + */ +static inline struct dma_async_tx_descriptor * +dmaengine_prep_config_single_safe(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; + + sg_init_table(&sg, 1); + sg_dma_address(&sg) = buf; + sg_dma_len(&sg) = len; + + return dmaengine_prep_config_sg_safe(chan, &sg, 1, dir, flags, config); +} + #ifdef CONFIG_RAPIDIO_DMA_ENGINE struct rio_dma_ext; static inline struct dma_async_tx_descriptor *dmaengine_prep_rio_sg( From 9605825841061bbdd2fc2a0218098373c539173e Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:49 -0400 Subject: [PATCH 3/9] PCI: endpoint: pci-epf-test: Use dmaengine_prep_config_single() to simplify code Use dmaengine_prep_config_single() to simplify code. No functional change. Tested-by: Niklas Cassel Reviewed-by: Damien Le Moal Acked-by: Manivannan Sadhasivam Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-3-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/pci/endpoint/functions/pci-epf-test.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c index 4802d4f80f78..d4905aa8e4c0 100644 --- a/drivers/pci/endpoint/functions/pci-epf-test.c +++ b/drivers/pci/endpoint/functions/pci-epf-test.c @@ -183,12 +183,8 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test, else sconf.src_addr = dma_remote; - if (dmaengine_slave_config(chan, &sconf)) { - dev_err(dev, "DMA slave config fail\n"); - return -EIO; - } - tx = dmaengine_prep_slave_single(chan, dma_local, len, dir, - flags); + tx = dmaengine_prep_config_single(chan, dma_local, len, + dir, flags, &sconf); } else { tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags); From bfb66d8098dbbaaada3ab877eda21cd447115c95 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:50 -0400 Subject: [PATCH 4/9] dmaengine: dw-edma: Use new .device_prep_config_sg() callback Use the new .device_prep_config_sg() callback to combine configuration and descriptor preparation. No functional changes. Tested-by: Niklas Cassel Reviewed-by: Damien Le Moal Reviewed-by: Manivannan Sadhasivam Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-4-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/dma/dw-edma/dw-edma-core.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c index 89a4c498a17b..8c192d63113c 100644 --- a/drivers/dma/dw-edma/dw-edma-core.c +++ b/drivers/dma/dw-edma/dw-edma-core.c @@ -577,10 +577,11 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer) } static struct dma_async_tx_descriptor * -dw_edma_device_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl, - unsigned int len, - enum dma_transfer_direction direction, - unsigned long flags, void *context) +dw_edma_device_prep_config_sg(struct dma_chan *dchan, struct scatterlist *sgl, + unsigned int len, + enum dma_transfer_direction direction, + unsigned long flags, + struct dma_slave_config *config) { struct dw_edma_transfer xfer; @@ -591,6 +592,9 @@ dw_edma_device_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl, xfer.flags = flags; xfer.type = EDMA_XFER_SCATTER_GATHER; + if (config && dw_edma_device_config(dchan, config)) + return NULL; + return dw_edma_device_transfer(&xfer); } @@ -970,7 +974,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc) dma->device_terminate_all = dw_edma_device_terminate_all; dma->device_issue_pending = dw_edma_device_issue_pending; dma->device_tx_status = dw_edma_device_tx_status; - dma->device_prep_slave_sg = dw_edma_device_prep_slave_sg; + dma->device_prep_config_sg = dw_edma_device_prep_config_sg; dma->device_prep_dma_cyclic = dw_edma_device_prep_dma_cyclic; dma->device_prep_interleaved_dma = dw_edma_device_prep_interleaved_dma; From 1af246e9d222f93aee59f3b47ff3bd59d08725e7 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:51 -0400 Subject: [PATCH 5/9] dmaengine: dw-edma: Pass dma_slave_config to dw_edma_device_transfer() Pass dma_slave_config to dw_edma_device_transfer() to support atomic configuration and descriptor preparation when a non-NULL config is provided to device_prep_config_sg(). Tested-by: Niklas Cassel Reviewed-by: Manivannan Sadhasivam Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-5-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/dma/dw-edma/dw-edma-core.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c index 8c192d63113c..1fec1b52e3d4 100644 --- a/drivers/dma/dw-edma/dw-edma-core.c +++ b/drivers/dma/dw-edma/dw-edma-core.c @@ -267,6 +267,20 @@ static int dw_edma_device_config(struct dma_chan *dchan, return 0; } +static struct dma_slave_config * +dw_edma_device_get_config(struct dma_chan *dchan, + struct dma_slave_config *config) +{ + struct dw_edma_chan *chan; + + if (config) + return config; + + chan = dchan2dw_edma_chan(dchan); + + return &chan->config; +} + static int dw_edma_device_pause(struct dma_chan *dchan) { struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan); @@ -385,7 +399,8 @@ dw_edma_device_tx_status(struct dma_chan *dchan, dma_cookie_t cookie, } static struct dma_async_tx_descriptor * -dw_edma_device_transfer(struct dw_edma_transfer *xfer) +dw_edma_device_transfer(struct dw_edma_transfer *xfer, + struct dma_slave_config *config) { struct dw_edma_chan *chan = dchan2dw_edma_chan(xfer->dchan); enum dma_transfer_direction dir = xfer->direction; @@ -472,8 +487,8 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer) src_addr = xfer->xfer.il->src_start; dst_addr = xfer->xfer.il->dst_start; } else { - src_addr = chan->config.src_addr; - dst_addr = chan->config.dst_addr; + src_addr = config->src_addr; + dst_addr = config->dst_addr; } if (dir == DMA_DEV_TO_MEM) @@ -595,7 +610,7 @@ dw_edma_device_prep_config_sg(struct dma_chan *dchan, struct scatterlist *sgl, if (config && dw_edma_device_config(dchan, config)) return NULL; - return dw_edma_device_transfer(&xfer); + return dw_edma_device_transfer(&xfer, dw_edma_device_get_config(dchan, config)); } static struct dma_async_tx_descriptor * @@ -614,7 +629,7 @@ dw_edma_device_prep_dma_cyclic(struct dma_chan *dchan, dma_addr_t paddr, xfer.flags = flags; xfer.type = EDMA_XFER_CYCLIC; - return dw_edma_device_transfer(&xfer); + return dw_edma_device_transfer(&xfer, dw_edma_device_get_config(dchan, NULL)); } static struct dma_async_tx_descriptor * @@ -630,7 +645,7 @@ dw_edma_device_prep_interleaved_dma(struct dma_chan *dchan, xfer.flags = flags; xfer.type = EDMA_XFER_INTERLEAVED; - return dw_edma_device_transfer(&xfer); + return dw_edma_device_transfer(&xfer, dw_edma_device_get_config(dchan, NULL)); } static void dw_hdma_set_callback_result(struct virt_dma_desc *vd, From bd00d2c4a1b2a1e7ad3060d3d606fb4c9db6a064 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:52 -0400 Subject: [PATCH 6/9] nvmet: pci-epf: Remove unnecessary dmaengine_terminate_sync() on each DMA transfer dmaengine_terminate_sync() cancels all pending requests. Calling it for every DMA transfer is unnecessary and counterproductive. This function is generally intended for cleanup paths such as module removal, device close, or unbind operations. Remove the redundant calls for success path and keep it only at error path. Tested-by: Niklas Cassel Reviewed-by: Damien Le Moal Acked-by: Manivannan Sadhasivam Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-6-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/nvme/target/pci-epf.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/nvme/target/pci-epf.c b/drivers/nvme/target/pci-epf.c index 4e9db96ebfec..2afe8f4d0e46 100644 --- a/drivers/nvme/target/pci-epf.c +++ b/drivers/nvme/target/pci-epf.c @@ -420,10 +420,9 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf, if (dma_sync_wait(chan, cookie) != DMA_COMPLETE) { dev_err(dev, "DMA transfer failed\n"); ret = -EIO; + dmaengine_terminate_sync(chan); } - dmaengine_terminate_sync(chan); - unmap: dma_unmap_single(dma_dev, dma_addr, seg->length, dir); From a0fba0a49f77effd3962723b1fa14c766fbc0ec4 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:53 -0400 Subject: [PATCH 7/9] nvmet: pci-epf: Use dmaengine_prep_config_single_safe() API Use the new dmaengine_prep_config_single_safe() API to combine the configuration and descriptor preparation into a single call. Since dmaengine_prep_config_single_safe() performs the configuration and preparation atomically and the mutex can be removed. Tested-by: Niklas Cassel Acked-by: Manivannan Sadhasivam Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-7-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/nvme/target/pci-epf.c | 30 ++++-------------------------- 1 file changed, 4 insertions(+), 26 deletions(-) diff --git a/drivers/nvme/target/pci-epf.c b/drivers/nvme/target/pci-epf.c index 2afe8f4d0e46..b1ba2d0bea6d 100644 --- a/drivers/nvme/target/pci-epf.c +++ b/drivers/nvme/target/pci-epf.c @@ -210,9 +210,7 @@ struct nvmet_pci_epf { bool dma_enabled; struct dma_chan *dma_tx_chan; - struct mutex dma_tx_lock; struct dma_chan *dma_rx_chan; - struct mutex dma_rx_lock; struct mutex mmio_lock; @@ -295,9 +293,6 @@ static void nvmet_pci_epf_init_dma(struct nvmet_pci_epf *nvme_epf) struct dma_chan *chan; dma_cap_mask_t mask; - mutex_init(&nvme_epf->dma_rx_lock); - mutex_init(&nvme_epf->dma_tx_lock); - dma_cap_zero(mask); dma_cap_set(DMA_SLAVE, mask); @@ -336,8 +331,6 @@ static void nvmet_pci_epf_init_dma(struct nvmet_pci_epf *nvme_epf) nvme_epf->dma_rx_chan = NULL; out_dma_no_rx: - mutex_destroy(&nvme_epf->dma_rx_lock); - mutex_destroy(&nvme_epf->dma_tx_lock); nvme_epf->dma_enabled = false; dev_info(&epf->dev, "DMA not supported, falling back to MMIO\n"); @@ -352,8 +345,6 @@ static void nvmet_pci_epf_deinit_dma(struct nvmet_pci_epf *nvme_epf) nvme_epf->dma_tx_chan = NULL; dma_release_channel(nvme_epf->dma_rx_chan); nvme_epf->dma_rx_chan = NULL; - mutex_destroy(&nvme_epf->dma_rx_lock); - mutex_destroy(&nvme_epf->dma_tx_lock); nvme_epf->dma_enabled = false; } @@ -368,18 +359,15 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf, struct dma_chan *chan; dma_cookie_t cookie; dma_addr_t dma_addr; - struct mutex *lock; int ret; switch (dir) { case DMA_FROM_DEVICE: - lock = &nvme_epf->dma_rx_lock; chan = nvme_epf->dma_rx_chan; sconf.direction = DMA_DEV_TO_MEM; sconf.src_addr = seg->pci_addr; break; case DMA_TO_DEVICE: - lock = &nvme_epf->dma_tx_lock; chan = nvme_epf->dma_tx_chan; sconf.direction = DMA_MEM_TO_DEV; sconf.dst_addr = seg->pci_addr; @@ -388,22 +376,15 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf, return -EINVAL; } - mutex_lock(lock); - dma_dev = dmaengine_get_dma_device(chan); dma_addr = dma_map_single(dma_dev, seg->buf, seg->length, dir); ret = dma_mapping_error(dma_dev, dma_addr); if (ret) - goto unlock; + return ret; - ret = dmaengine_slave_config(chan, &sconf); - if (ret) { - dev_err(dev, "Failed to configure DMA channel\n"); - goto unmap; - } - - desc = dmaengine_prep_slave_single(chan, dma_addr, seg->length, - sconf.direction, DMA_CTRL_ACK); + desc = dmaengine_prep_config_single_safe(chan, dma_addr, seg->length, + sconf.direction, + DMA_CTRL_ACK, &sconf); if (!desc) { dev_err(dev, "Failed to prepare DMA\n"); ret = -EIO; @@ -426,9 +407,6 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf, unmap: dma_unmap_single(dma_dev, dma_addr, seg->length, dir); -unlock: - mutex_unlock(lock); - return ret; } From 53191cc449db1cf4f25db275978c61b1c6aaeba9 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:54 -0400 Subject: [PATCH 8/9] PCI: epf-mhi: Use dmaengine_prep_config_single() to simplify code Use dmaengine_prep_config_single() to simplify pci_epf_mhi_edma_read[_sync]() and pci_epf_mhi_edma_write[_sync](). No functional change. Tested-by: Niklas Cassel Acked-by: Manivannan Sadhasivam Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-8-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/pci/endpoint/functions/pci-epf-mhi.c | 52 ++++++-------------- 1 file changed, 16 insertions(+), 36 deletions(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-mhi.c b/drivers/pci/endpoint/functions/pci-epf-mhi.c index 7f5326925ed5..c3e3b58fb86c 100644 --- a/drivers/pci/endpoint/functions/pci-epf-mhi.c +++ b/drivers/pci/endpoint/functions/pci-epf-mhi.c @@ -328,12 +328,6 @@ static int pci_epf_mhi_edma_read(struct mhi_ep_cntrl *mhi_cntrl, config.direction = DMA_DEV_TO_MEM; config.src_addr = buf_info->host_addr; - ret = dmaengine_slave_config(chan, &config); - if (ret) { - dev_err(dev, "Failed to configure DMA channel\n"); - goto err_unlock; - } - dst_addr = dma_map_single(dma_dev, buf_info->dev_addr, buf_info->size, DMA_FROM_DEVICE); ret = dma_mapping_error(dma_dev, dst_addr); @@ -342,9 +336,10 @@ static int pci_epf_mhi_edma_read(struct mhi_ep_cntrl *mhi_cntrl, goto err_unlock; } - desc = dmaengine_prep_slave_single(chan, dst_addr, buf_info->size, - DMA_DEV_TO_MEM, - DMA_CTRL_ACK | DMA_PREP_INTERRUPT); + desc = dmaengine_prep_config_single(chan, dst_addr, buf_info->size, + DMA_DEV_TO_MEM, + DMA_CTRL_ACK | DMA_PREP_INTERRUPT, + &config); if (!desc) { dev_err(dev, "Failed to prepare DMA\n"); ret = -EIO; @@ -401,12 +396,6 @@ static int pci_epf_mhi_edma_write(struct mhi_ep_cntrl *mhi_cntrl, config.direction = DMA_MEM_TO_DEV; config.dst_addr = buf_info->host_addr; - ret = dmaengine_slave_config(chan, &config); - if (ret) { - dev_err(dev, "Failed to configure DMA channel\n"); - goto err_unlock; - } - src_addr = dma_map_single(dma_dev, buf_info->dev_addr, buf_info->size, DMA_TO_DEVICE); ret = dma_mapping_error(dma_dev, src_addr); @@ -415,9 +404,10 @@ static int pci_epf_mhi_edma_write(struct mhi_ep_cntrl *mhi_cntrl, goto err_unlock; } - desc = dmaengine_prep_slave_single(chan, src_addr, buf_info->size, - DMA_MEM_TO_DEV, - DMA_CTRL_ACK | DMA_PREP_INTERRUPT); + desc = dmaengine_prep_config_single(chan, src_addr, buf_info->size, + DMA_MEM_TO_DEV, + DMA_CTRL_ACK | DMA_PREP_INTERRUPT, + &config); if (!desc) { dev_err(dev, "Failed to prepare DMA\n"); ret = -EIO; @@ -506,12 +496,6 @@ static int pci_epf_mhi_edma_read_async(struct mhi_ep_cntrl *mhi_cntrl, config.direction = DMA_DEV_TO_MEM; config.src_addr = buf_info->host_addr; - ret = dmaengine_slave_config(chan, &config); - if (ret) { - dev_err(dev, "Failed to configure DMA channel\n"); - goto err_unlock; - } - dst_addr = dma_map_single(dma_dev, buf_info->dev_addr, buf_info->size, DMA_FROM_DEVICE); ret = dma_mapping_error(dma_dev, dst_addr); @@ -520,9 +504,10 @@ static int pci_epf_mhi_edma_read_async(struct mhi_ep_cntrl *mhi_cntrl, goto err_unlock; } - desc = dmaengine_prep_slave_single(chan, dst_addr, buf_info->size, - DMA_DEV_TO_MEM, - DMA_CTRL_ACK | DMA_PREP_INTERRUPT); + desc = dmaengine_prep_config_single(chan, dst_addr, buf_info->size, + DMA_DEV_TO_MEM, + DMA_CTRL_ACK | DMA_PREP_INTERRUPT, + &config); if (!desc) { dev_err(dev, "Failed to prepare DMA\n"); ret = -EIO; @@ -585,12 +570,6 @@ static int pci_epf_mhi_edma_write_async(struct mhi_ep_cntrl *mhi_cntrl, config.direction = DMA_MEM_TO_DEV; config.dst_addr = buf_info->host_addr; - ret = dmaengine_slave_config(chan, &config); - if (ret) { - dev_err(dev, "Failed to configure DMA channel\n"); - goto err_unlock; - } - src_addr = dma_map_single(dma_dev, buf_info->dev_addr, buf_info->size, DMA_TO_DEVICE); ret = dma_mapping_error(dma_dev, src_addr); @@ -599,9 +578,10 @@ static int pci_epf_mhi_edma_write_async(struct mhi_ep_cntrl *mhi_cntrl, goto err_unlock; } - desc = dmaengine_prep_slave_single(chan, src_addr, buf_info->size, - DMA_MEM_TO_DEV, - DMA_CTRL_ACK | DMA_PREP_INTERRUPT); + desc = dmaengine_prep_config_single(chan, src_addr, buf_info->size, + DMA_MEM_TO_DEV, + DMA_CTRL_ACK | DMA_PREP_INTERRUPT, + &config); if (!desc) { dev_err(dev, "Failed to prepare DMA\n"); ret = -EIO; From c9e9927c6d8346cdf6555a8f97da093980172e4b Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 21 May 2026 11:32:55 -0400 Subject: [PATCH 9/9] crypto: atmel: Use dmaengine_prep_config_sg() API Using new API dmaengine_prep_config_sg() to simple code. dmaengine_prep_config_sg() does not distinguish between configuration failures and descriptor preparation failures, as both are reported through a NULL return value. Converting both cases to -ENOMEM is therefore acceptable and consistent with the helper's abstraction. In practice, most users only care whether the operation succeeds or fails, and do not depend on the exact errno value returned from this path. Tested-by: Niklas Cassel Acked-by: Nicolas Ferre Signed-off-by: Frank Li Link: https://patch.msgid.link/20260521-dma_prep_config-v7-9-1f73f4899883@nxp.com Signed-off-by: Vinod Koul --- drivers/crypto/atmel-aes.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c index b393689400b4..d890b5a277b9 100644 --- a/drivers/crypto/atmel-aes.c +++ b/drivers/crypto/atmel-aes.c @@ -795,7 +795,6 @@ static int atmel_aes_dma_transfer_start(struct atmel_aes_dev *dd, struct dma_slave_config config; dma_async_tx_callback callback; struct atmel_aes_dma *dma; - int err; memset(&config, 0, sizeof(config)); config.src_addr_width = addr_width; @@ -820,12 +819,9 @@ static int atmel_aes_dma_transfer_start(struct atmel_aes_dev *dd, return -EINVAL; } - err = dmaengine_slave_config(dma->chan, &config); - if (err) - return err; - - desc = dmaengine_prep_slave_sg(dma->chan, dma->sg, dma->sg_len, dir, - DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + desc = dmaengine_prep_config_sg(dma->chan, dma->sg, dma->sg_len, dir, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK, + &config); if (!desc) return -ENOMEM;