Re: [PATCH RESEND v10 2/2] dmaengine: dw-edma: Add non-LL mode

[Frank Li]

On Mon, Feb 16, 2026 at 04:25:46PM +0530, Devendra K Verma wrote:
> AMD MDB IP supports Linked List (LL) mode as well as non-LL mode.
> The current code does not have the mechanisms to enable the
> DMA transactions using the non-LL mode. The following two cases
> are added with this patch:
> - For the AMD (Xilinx) only, when a valid physical base address of
>   the device side DDR is not configured, then the IP can still be
>   used in non-LL mode. For all the channels DMA transactions will
>   be using the non-LL mode only. This, the default non-LL mode,
>   is not applicable for Synopsys IP with the current code addition.
>
> - If the default mode is LL-mode, for both AMD (Xilinx) and Synosys,
>   and if user wants to use non-LL mode then user can do so via
>   configuring the peripheral_config param of dma_slave_config.
>
> Signed-off-by: Devendra K Verma <devendra.verma@xxxxxxx>
> ---
> Changes in v10
>   Added the peripheral_config check only for HDMA IP in
>   dw_edma_device_config().
>   Replaced the loop with single entry retrieval for non-LL
>   mode.
>   Addressed review comments and handled the burst allocation
>   by defining 'bursts_max' as per suggestions.
>
> Changes in v9
>   Fixed compilation errors related to macro name mismatch.
>
> Changes in v8
>   Cosmetic change related to comment and code.
>
> Changes in v7
>   No change
>
> Changes in v6
>   Gave definition to bits used for channel configuration.
>   Removed the comment related to doorbell.
>
> Changes in v5
>   Variable name 'nollp' changed to 'non_ll'.
>   In the dw_edma_device_config() WARN_ON replaced with dev_err().
>   Comments follow the 80-column guideline.
>
> Changes in v4
>   No change
>
> Changes in v3
>   No change
>
> Changes in v2
>   Reverted the function return type to u64 for
>   dw_edma_get_phys_addr().
>
> Changes in v1
>   Changed the function return type for dw_edma_get_phys_addr().
>   Corrected the typo raised in review.
> ---
>  drivers/dma/dw-edma/dw-edma-core.c    | 35 ++++++++++++++-
>  drivers/dma/dw-edma/dw-edma-core.h    |  1 +
>  drivers/dma/dw-edma/dw-edma-pcie.c    | 44 ++++++++++++------
>  drivers/dma/dw-edma/dw-hdma-v0-core.c | 65 ++++++++++++++++++++++++++-
>  drivers/dma/dw-edma/dw-hdma-v0-regs.h |  1 +
>  include/linux/dma/edma.h              |  1 +
>  6 files changed, 132 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index b43255f914f3..ef3d79a9f88d 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -223,6 +223,31 @@ static int dw_edma_device_config(struct dma_chan *dchan,
>  				 struct dma_slave_config *config)
>  {
>  	struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
> +	int non_ll = 0;
> +
> +	chan->non_ll = false;
> +	if (chan->dw->chip->mf == EDMA_MF_HDMA_NATIVE) {

Need handle EMDA case. if mf is EDMA, need return error when
config->peripheral_config is not NULL. Or remove above check to make
code work for both EDMA or HDMA.

> +		if (config->peripheral_config &&
> +		    config->peripheral_size != sizeof(int)) {
> +			dev_err(dchan->device->dev,
> +				"config param peripheral size mismatch\n");
> +			return -EINVAL;
> +		}
> +
> +		/*
> +		 * When there is no valid LLP base address available then the
> +		 * default DMA ops will use the non-LL mode.
> +		 *
> +		 * Cases where LL mode is enabled and client wants to use the
> +		 * non-LL mode then also client can do so via providing the
> +		 * peripheral_config param.
> +		 */
> +		if (config->peripheral_config)
> +			non_ll = *(int *)config->peripheral_config;
> +
> +		if (chan->dw->chip->non_ll || (!chan->dw->chip->non_ll && non_ll))

if chan->dw->chip->non_ll is true, It should return error if you set non_ll
false because no LLP base available.

> +			chan->non_ll = true;
> +	}
>
>  	memcpy(&chan->config, config, sizeof(*config));
>  	chan->configured = true;
> @@ -358,6 +383,7 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
>  	struct dw_edma_desc *desc;
>  	u64 src_addr, dst_addr;
>  	size_t fsz = 0;
> +	u32 bursts_max;
>  	u32 cnt = 0;
>  	int i;
>
> @@ -415,6 +441,13 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
>  		return NULL;
>  	}
>
> +	/*
> +	 * For non-LL mode, only a single burst can be handled
> +	 * in a single chunk unlike LL mode where multiple bursts
> +	 * can be configured in a single chunk.
> +	 */
> +	bursts_max = chan->non_ll ? 1 : chan->ll_max;
> +
>  	desc = dw_edma_alloc_desc(chan);
>  	if (unlikely(!desc))
>  		goto err_alloc;
> @@ -450,7 +483,7 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer)
>  		if (xfer->type == EDMA_XFER_SCATTER_GATHER && !sg)
>  			break;
>
> -		if (chunk->bursts_alloc == chan->ll_max) {
> +		if (chunk->bursts_alloc == bursts_max) {
>  			chunk = dw_edma_alloc_chunk(desc);
>  			if (unlikely(!chunk))
>  				goto err_alloc;
> diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
> index 71894b9e0b15..c8e3d196a549 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.h
> +++ b/drivers/dma/dw-edma/dw-edma-core.h
> @@ -86,6 +86,7 @@ struct dw_edma_chan {
>  	u8				configured;
>
>  	struct dma_slave_config		config;
> +	bool				non_ll;
>  };
>
>  struct dw_edma_irq {
> diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-edma-pcie.c
> index 3aefc48f8e0a..94621b0f87df 100644
> --- a/drivers/dma/dw-edma/dw-edma-pcie.c
> +++ b/drivers/dma/dw-edma/dw-edma-pcie.c
> @@ -295,6 +295,15 @@ static void dw_edma_pcie_get_xilinx_dma_data(struct pci_dev *pdev,
>  	pdata->devmem_phys_off = off;
>  }
>
> +static u64 dw_edma_get_phys_addr(struct pci_dev *pdev,
> +				 struct dw_edma_pcie_data *pdata,
> +				 enum pci_barno bar)
> +{
> +	if (pdev->vendor == PCI_VENDOR_ID_XILINX)
> +		return pdata->devmem_phys_off;
> +	return pci_bus_address(pdev, bar);
> +}
> +
>  static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  			      const struct pci_device_id *pid)
>  {
> @@ -304,6 +313,7 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  	struct dw_edma_chip *chip;
>  	int err, nr_irqs;
>  	int i, mask;
> +	bool non_ll = false;
>
>  	vsec_data = kmalloc(sizeof(*vsec_data), GFP_KERNEL);
>  	if (!vsec_data)
> @@ -329,21 +339,24 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>
>  		/*
>  		 * There is no valid address found for the LL memory
> -		 * space on the device side.
> +		 * space on the device side. In the absence of LL base
> +		 * address use the non-LL mode or simple mode supported by
> +		 * the HDMA IP.
>  		 */
>  		if (vsec_data->devmem_phys_off == DW_PCIE_XILINX_MDB_INVALID_ADDR)
> -			return -ENOMEM;
> +			non_ll = true;
>
>  		/*
>  		 * Configure the channel LL and data blocks if number of
>  		 * channels enabled in VSEC capability are more than the
>  		 * channels configured in xilinx_mdb_data.
>  		 */
> -		dw_edma_set_chan_region_offset(vsec_data, BAR_2, 0,
> -					       DW_PCIE_XILINX_MDB_LL_OFF_GAP,
> -					       DW_PCIE_XILINX_MDB_LL_SIZE,
> -					       DW_PCIE_XILINX_MDB_DT_OFF_GAP,
> -					       DW_PCIE_XILINX_MDB_DT_SIZE);
> +		if (!non_ll)
> +			dw_edma_set_chan_region_offset(vsec_data, BAR_2, 0,
> +						       DW_PCIE_XILINX_MDB_LL_OFF_GAP,
> +						       DW_PCIE_XILINX_MDB_LL_SIZE,
> +						       DW_PCIE_XILINX_MDB_DT_OFF_GAP,
> +						       DW_PCIE_XILINX_MDB_DT_SIZE);
>  	}
>
>  	/* Mapping PCI BAR regions */
> @@ -391,6 +404,7 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  	chip->mf = vsec_data->mf;
>  	chip->nr_irqs = nr_irqs;
>  	chip->ops = &dw_edma_pcie_plat_ops;
> +	chip->non_ll = non_ll;
>
>  	chip->ll_wr_cnt = vsec_data->wr_ch_cnt;
>  	chip->ll_rd_cnt = vsec_data->rd_ch_cnt;
> @@ -399,7 +413,7 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  	if (!chip->reg_base)
>  		return -ENOMEM;
>
> -	for (i = 0; i < chip->ll_wr_cnt; i++) {
> +	for (i = 0; i < chip->ll_wr_cnt && !non_ll; i++) {
>  		struct dw_edma_region *ll_region = &chip->ll_region_wr[i];
>  		struct dw_edma_region *dt_region = &chip->dt_region_wr[i];
>  		struct dw_edma_block *ll_block = &vsec_data->ll_wr[i];
> @@ -410,7 +424,8 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  			return -ENOMEM;
>
>  		ll_region->vaddr.io += ll_block->off;
> -		ll_region->paddr = pci_bus_address(pdev, ll_block->bar);
> +		ll_region->paddr = dw_edma_get_phys_addr(pdev, vsec_data,
> +							 ll_block->bar);
>  		ll_region->paddr += ll_block->off;
>  		ll_region->sz = ll_block->sz;
>
> @@ -419,12 +434,13 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  			return -ENOMEM;
>
>  		dt_region->vaddr.io += dt_block->off;
> -		dt_region->paddr = pci_bus_address(pdev, dt_block->bar);
> +		dt_region->paddr = dw_edma_get_phys_addr(pdev, vsec_data,
> +							 dt_block->bar);
>  		dt_region->paddr += dt_block->off;
>  		dt_region->sz = dt_block->sz;
>  	}
>
> -	for (i = 0; i < chip->ll_rd_cnt; i++) {
> +	for (i = 0; i < chip->ll_rd_cnt && !non_ll; i++) {
>  		struct dw_edma_region *ll_region = &chip->ll_region_rd[i];
>  		struct dw_edma_region *dt_region = &chip->dt_region_rd[i];
>  		struct dw_edma_block *ll_block = &vsec_data->ll_rd[i];
> @@ -435,7 +451,8 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  			return -ENOMEM;
>
>  		ll_region->vaddr.io += ll_block->off;
> -		ll_region->paddr = pci_bus_address(pdev, ll_block->bar);
> +		ll_region->paddr = dw_edma_get_phys_addr(pdev, vsec_data,
> +							 ll_block->bar);
>  		ll_region->paddr += ll_block->off;
>  		ll_region->sz = ll_block->sz;
>
> @@ -444,7 +461,8 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  			return -ENOMEM;
>
>  		dt_region->vaddr.io += dt_block->off;
> -		dt_region->paddr = pci_bus_address(pdev, dt_block->bar);
> +		dt_region->paddr = dw_edma_get_phys_addr(pdev, vsec_data,
> +							 dt_block->bar);
>  		dt_region->paddr += dt_block->off;
>  		dt_region->sz = dt_block->sz;
>  	}
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> index e3f8db4fe909..a1b04fec6310 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> @@ -225,7 +225,7 @@ static void dw_hdma_v0_sync_ll_data(struct dw_edma_chunk *chunk)
>  		readl(chunk->ll_region.vaddr.io);
>  }
>
> -static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
> +static void dw_hdma_v0_core_ll_start(struct dw_edma_chunk *chunk, bool first)
>  {
>  	struct dw_edma_chan *chan = chunk->chan;
>  	struct dw_edma *dw = chan->dw;
> @@ -263,6 +263,69 @@ static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
>  	SET_CH_32(dw, chan->dir, chan->id, doorbell, HDMA_V0_DOORBELL_START);
>  }
>
> +static void dw_hdma_v0_core_non_ll_start(struct dw_edma_chunk *chunk)
> +{
> +	struct dw_edma_chan *chan = chunk->chan;
> +	struct dw_edma *dw = chan->dw;
> +	struct dw_edma_burst *child;
> +	u32 val;
> +
> +	child = list_first_entry_or_null(&chunk->burst->list,
> +					 struct dw_edma_burst, list);
> +	if (!child)
> +		return;
> +
> +	SET_CH_32(dw, chan->dir, chan->id, ch_en, HDMA_V0_CH_EN);
> +
> +	/* Source address */
> +	SET_CH_32(dw, chan->dir, chan->id, sar.lsb,
> +		  lower_32_bits(child->sar));
> +	SET_CH_32(dw, chan->dir, chan->id, sar.msb,
> +		  upper_32_bits(child->sar));
> +
> +	/* Destination address */
> +	SET_CH_32(dw, chan->dir, chan->id, dar.lsb,
> +		  lower_32_bits(child->dar));
> +	SET_CH_32(dw, chan->dir, chan->id, dar.msb,
> +		  upper_32_bits(child->dar));
> +
> +	/* Transfer size */
> +	SET_CH_32(dw, chan->dir, chan->id, transfer_size, child->sz);
> +
> +	/* Interrupt setup */
> +	val = GET_CH_32(dw, chan->dir, chan->id, int_setup) |
> +			HDMA_V0_STOP_INT_MASK |
> +			HDMA_V0_ABORT_INT_MASK |
> +			HDMA_V0_LOCAL_STOP_INT_EN |
> +			HDMA_V0_LOCAL_ABORT_INT_EN;
> +
> +	if (!(dw->chip->flags & DW_EDMA_CHIP_LOCAL)) {
> +		val |= HDMA_V0_REMOTE_STOP_INT_EN |
> +		       HDMA_V0_REMOTE_ABORT_INT_EN;
> +	}
> +
> +	SET_CH_32(dw, chan->dir, chan->id, int_setup, val);
> +
> +	/* Channel control setup */
> +	val = GET_CH_32(dw, chan->dir, chan->id, control1);
> +	val &= ~HDMA_V0_LINKLIST_EN;
> +	SET_CH_32(dw, chan->dir, chan->id, control1, val);
> +
> +	SET_CH_32(dw, chan->dir, chan->id, doorbell,
> +		  HDMA_V0_DOORBELL_START);
> +
> +}
> +
> +static void dw_hdma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
> +{
> +	struct dw_edma_chan *chan = chunk->chan;
> +
> +	if (chan->non_ll)
> +		dw_hdma_v0_core_non_ll_start(chunk);
> +	else
> +		dw_hdma_v0_core_ll_start(chunk, first);
> +}
> +
>  static void dw_hdma_v0_core_ch_config(struct dw_edma_chan *chan)
>  {
>  	struct dw_edma *dw = chan->dw;
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-regs.h b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> index eab5fd7177e5..7759ba9b4850 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-regs.h
> @@ -12,6 +12,7 @@
>  #include <linux/dmaengine.h>
>
>  #define HDMA_V0_MAX_NR_CH			8
> +#define HDMA_V0_CH_EN				BIT(0)
>  #define HDMA_V0_LOCAL_ABORT_INT_EN		BIT(6)
>  #define HDMA_V0_REMOTE_ABORT_INT_EN		BIT(5)
>  #define HDMA_V0_LOCAL_STOP_INT_EN		BIT(4)
> diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
> index 3080747689f6..78ce31b049ae 100644
> --- a/include/linux/dma/edma.h
> +++ b/include/linux/dma/edma.h
> @@ -99,6 +99,7 @@ struct dw_edma_chip {
>  	enum dw_edma_map_format	mf;
>
>  	struct dw_edma		*dw;
> +	bool			non_ll;

Can you check ll_region directly? it should be equal to
(ll_region->sz == 0) ?

Frank
>  };
>
>  /* Export to the platform drivers */
> --
> 2.43.0
>