Re: [PATCH v2 02/12] dmaengine: dw-edma: Add per-channel interrupt routing control

[Frank Li]

On Mon, May 25, 2026 at 03:24:10PM +0900, Koichiro Den wrote:
> DesignWare eDMA can signal completion locally through edma_int[] and
> remotely through IMWr/MSI. When channels are delegated to a remote
> frontend, the local endpoint side and the remote host side must not both
> service the same DONE/ABORT status.
>
> Add dw_edma_irq_config, carried through dma_slave_config, so a frontend
> can choose default, local, or remote IRQ handling per channel. Update the
> v0 path so linked-list interrupt generation and DONE/ABORT masking follow
> the selected mode. If a frontend does not supply the config, keep the
> existing behavior.
>
> HDMA native already uses dma_slave_config.peripheral_config as an int for
> non-LL mode selection. Keep that interface unchanged and reject the new
> IRQ config there until an IRQ routing model is implemented and validated.
>
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> ---
...
>
> +static inline bool
> +dw_edma_core_ch_ignore_irq(struct dw_edma_chan *chan)
> +{
> +	struct dw_edma *dw = chan->dw;
> +
> +	if (dw->chip->flags & DW_EDMA_CHIP_LOCAL)

suppose it should be pre channel config, why need check chip's informaiton?

> +		return chan->irq_mode == DW_EDMA_CH_IRQ_REMOTE;
> +	else
> +		return chan->irq_mode == DW_EDMA_CH_IRQ_LOCAL;
> +}
> +
>  #endif /* _DW_EDMA_CORE_H */
> diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
> index 69e8279adec8..08ec2bd7856e 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> @@ -256,9 +256,11 @@ dw_edma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
>  	for_each_set_bit(pos, &val, total) {
>  		chan = &dw->chan[pos + off];
>
> +		if (dw_edma_core_ch_ignore_irq(chan))
> +			continue;
> +
>  		dw_edma_v0_core_clear_done_int(chan);
>  		done(chan);
> -
>  		ret = IRQ_HANDLED;
>  	}
>
> @@ -267,9 +269,11 @@ dw_edma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
>  	for_each_set_bit(pos, &val, total) {
>  		chan = &dw->chan[pos + off];
>
> +		if (dw_edma_core_ch_ignore_irq(chan))
> +			continue;
> +
>  		dw_edma_v0_core_clear_abort_int(chan);
>  		abort(chan);
> -
>  		ret = IRQ_HANDLED;
>  	}
>
> @@ -331,7 +335,8 @@ static void dw_edma_v0_core_write_chunk(struct dw_edma_chunk *chunk)
>  		j--;
>  		if (!j) {
>  			control |= DW_EDMA_V0_LIE;
> -			if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL))
> +			if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) &&
> +			    chan->irq_mode != DW_EDMA_CH_IRQ_LOCAL)
>  				control |= DW_EDMA_V0_RIE;
>  		}
>
> @@ -407,10 +412,15 @@ static void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
>  				break;
>  			}
>  		}
> -		/* Interrupt unmask - done, abort */
> +		/* Interrupt mask/unmask - done, abort */
>  		tmp = GET_RW_32(dw, chan->dir, int_mask);
> -		tmp &= ~FIELD_PREP(EDMA_V0_DONE_INT_MASK, BIT(chan->id));
> -		tmp &= ~FIELD_PREP(EDMA_V0_ABORT_INT_MASK, BIT(chan->id));
> +		if (chan->irq_mode == DW_EDMA_CH_IRQ_REMOTE) {
> +			tmp |= FIELD_PREP(EDMA_V0_DONE_INT_MASK, BIT(chan->id));
> +			tmp |= FIELD_PREP(EDMA_V0_ABORT_INT_MASK, BIT(chan->id));
> +		} else {
> +			tmp &= ~FIELD_PREP(EDMA_V0_DONE_INT_MASK, BIT(chan->id));
> +			tmp &= ~FIELD_PREP(EDMA_V0_ABORT_INT_MASK, BIT(chan->id));
> +		}
>  		SET_RW_32(dw, chan->dir, int_mask, tmp);
>  		/* Linked list error */
>  		tmp = GET_RW_32(dw, chan->dir, linked_list_err_en);
> diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
> index 3e15cf83b784..2bf2298711e1 100644
> --- a/include/linux/dma/edma.h
> +++ b/include/linux/dma/edma.h
> @@ -60,6 +60,43 @@ enum dw_edma_chip_flags {
>  	DW_EDMA_CHIP_LOCAL	= BIT(0),
>  };
>
> +/**
> + * enum dw_edma_ch_irq_mode - per-channel interrupt routing control
> + * @DW_EDMA_CH_IRQ_DEFAULT:   keep legacy behavior

Feel like it make things complex, most likely use pcie ep probe, it should
be use DW_EDMA_CH_IRQ_LOCAL.

If probe from dw-edma-pcie.c, it should be use DW_EDMA_CH_IRQ_REMOTE.

Add default mode, it make check logic become complex.

Frank

> + * @DW_EDMA_CH_IRQ_LOCAL:     local interrupt only (edma_int[])
> + * @DW_EDMA_CH_IRQ_REMOTE:    remote interrupt only (IMWr/MSI),
> + *                            while masking local DONE/ABORT output.
> + *
> + * DesignWare EP eDMA can signal interrupts locally through the edma_int[]
> + * bus, and remotely using posted memory writes (IMWr) that may be
> + * interpreted as MSI/MSI-X by the RC.
> + *
> + * For the v0 eDMA programming path, DMA_*_INT_MASK gates the local edma_int[]
> + * assertion, while there is no dedicated per-channel mask for IMWr generation.
> + * To request a remote-only interrupt, Synopsys recommends setting both LIE and
> + * RIE, and masking the local interrupt in DMA_*_INT_MASK (rather than relying
> + * on LIE=0/RIE=1). See the DesignWare endpoint databook 5.40a, Non Linked
> + * List Mode interrupt handling ("Hint").
> + */
> +enum dw_edma_ch_irq_mode {
> +	DW_EDMA_CH_IRQ_DEFAULT	= 0,
> +	DW_EDMA_CH_IRQ_LOCAL,
> +	DW_EDMA_CH_IRQ_REMOTE,
> +};
> +
> +/**
> + * struct dw_edma_irq_config - dw-edma interrupt routing configuration
> + * @irq_mode: per-channel interrupt routing control.
> + * @reserved: must be zero.
> + *
> + * Pass this structure via dma_slave_config.peripheral_config and
> + * dma_slave_config.peripheral_size.
> + */
> +struct dw_edma_irq_config {
> +	enum dw_edma_ch_irq_mode irq_mode;
> +	u32 reserved;
> +};
> +
>  /**
>   * struct dw_edma_chip - representation of DesignWare eDMA controller hardware
>   * @dev:		 struct device of the eDMA controller
> @@ -76,6 +113,8 @@ enum dw_edma_chip_flags {
>   * @db_irq:		 Virtual IRQ dedicated to interrupt emulation
>   * @db_offset:		 Offset from DMA register base
>   * @mf:			 DMA register map format
> + * @default_irq_mode:	 default per-channel interrupt routing when client
> + *			 does not supply dw_edma_irq_config
>   * @dw:			 struct dw_edma that is filled by dw_edma_probe()
>   */
>  struct dw_edma_chip {
> @@ -101,6 +140,7 @@ struct dw_edma_chip {
>  	resource_size_t		db_offset;
>
>  	enum dw_edma_map_format	mf;
> +	enum dw_edma_ch_irq_mode	default_irq_mode;

suppose it is pre-channel config?

Frank
>
>  	struct dw_edma		*dw;
>  	bool			cfg_non_ll;
> --
> 2.51.0
>