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Message-ID: <aWkXyNzSsEB/LsVc@lizhi-Precision-Tower-5810>
Date: Thu, 15 Jan 2026 11:37:28 -0500
From: Frank Li <Frank.li@....com>
To: Devendra K Verma <devendra.verma@....com>
Cc: bhelgaas@...gle.com, mani@...nel.org, vkoul@...nel.org,
dmaengine@...r.kernel.org, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org, michal.simek@....com
Subject: Re: [PATCH v8 2/2] dmaengine: dw-edma: Add non-LL mode
On Fri, Jan 09, 2026 at 05:33:54PM +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
If DDR have not configured, where DATA send to in device side by non-LL
mode.
> 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@....com>
> ---
> 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 | 42 +++++++++++++++++++++---
> drivers/dma/dw-edma/dw-edma-core.h | 1 +
> drivers/dma/dw-edma/dw-edma-pcie.c | 46 ++++++++++++++++++--------
> drivers/dma/dw-edma/dw-hdma-v0-core.c | 61 ++++++++++++++++++++++++++++++++++-
> drivers/dma/dw-edma/dw-hdma-v0-regs.h | 1 +
edma-v0-core.c have not update, if don't support, at least need return
failure at dw_edma_device_config() when backend is eDMA.
> include/linux/dma/edma.h | 1 +
> 6 files changed, 132 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index b43255f..d37112b 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -223,8 +223,32 @@ 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;
> +
> + if (config->peripheral_config &&
> + config->peripheral_size != sizeof(int)) {
> + dev_err(dchan->device->dev,
> + "config param peripheral size mismatch\n");
> + return -EINVAL;
> + }
>
> memcpy(&chan->config, config, sizeof(*config));
> +
> + /*
> + * 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;
> +
> + chan->non_ll = false;
> + if (chan->dw->chip->non_ll || (!chan->dw->chip->non_ll && non_ll))
> + chan->non_ll = true;
> +
> chan->configured = true;
>
> return 0;
> @@ -353,7 +377,7 @@ static void dw_edma_device_issue_pending(struct dma_chan *dchan)
> struct dw_edma_chan *chan = dchan2dw_edma_chan(xfer->dchan);
> enum dma_transfer_direction dir = xfer->direction;
> struct scatterlist *sg = NULL;
> - struct dw_edma_chunk *chunk;
> + struct dw_edma_chunk *chunk = NULL;
> struct dw_edma_burst *burst;
> struct dw_edma_desc *desc;
> u64 src_addr, dst_addr;
> @@ -419,9 +443,11 @@ static void dw_edma_device_issue_pending(struct dma_chan *dchan)
> if (unlikely(!desc))
> goto err_alloc;
>
> - chunk = dw_edma_alloc_chunk(desc);
> - if (unlikely(!chunk))
> - goto err_alloc;
> + if (!chan->non_ll) {
> + chunk = dw_edma_alloc_chunk(desc);
> + if (unlikely(!chunk))
> + goto err_alloc;
> + }
non_ll is the same as ll_max = 1. (or 2, there are link back entry).
If you set ll_max = 1, needn't change this code.
>
> if (xfer->type == EDMA_XFER_INTERLEAVED) {
> src_addr = xfer->xfer.il->src_start;
> @@ -450,7 +476,13 @@ static void dw_edma_device_issue_pending(struct dma_chan *dchan)
> if (xfer->type == EDMA_XFER_SCATTER_GATHER && !sg)
> break;
>
> - if (chunk->bursts_alloc == chan->ll_max) {
> + /*
> + * 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.
> + */
> + if ((chunk && chunk->bursts_alloc == chan->ll_max) ||
> + chan->non_ll) {
> 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 71894b9..c8e3d19 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 2efd149..277ca50 100644
> --- a/drivers/dma/dw-edma/dw-edma-pcie.c
> +++ b/drivers/dma/dw-edma/dw-edma-pcie.c
> @@ -298,6 +298,15 @@ 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)
> {
> @@ -307,6 +316,7 @@ 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)
> @@ -331,21 +341,24 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
> if (pdev->vendor == PCI_VENDOR_ID_XILINX) {
> /*
> * 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;
> + if (vsec_data->devmem_phys_off == DW_PCIE_AMD_MDB_INVALID_ADDR)
> + 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_LL_OFF_GAP,
> + DW_PCIE_XILINX_LL_SIZE,
> + DW_PCIE_XILINX_DT_OFF_GAP,
> + DW_PCIE_XILINX_DT_SIZE);
> }
>
> /* Mapping PCI BAR regions */
> @@ -393,6 +406,7 @@ 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;
> @@ -401,7 +415,7 @@ 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];
> @@ -412,7 +426,8 @@ 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);
This change need do prepare patch, which only change pci_bus_address() to
dw_edma_get_phys_addr().
> ll_region->paddr += ll_block->off;
> ll_region->sz = ll_block->sz;
>
> @@ -421,12 +436,13 @@ 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];
> @@ -437,7 +453,8 @@ 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;
>
> @@ -446,7 +463,8 @@ 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 e3f8db4..a5d12bc 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 +263,65 @@ 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;
> +
> + list_for_each_entry(child, &chunk->burst->list, list) {
why need iterated list, it doesn't support ll. Need wait for irq to start
next one.
Frank
> + 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 eab5fd7..7759ba9 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 3080747..78ce31b 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;
> };
>
> /* Export to the platform drivers */
> --
> 1.8.3.1
>
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