linux-kernel - Re: [PATCH v3 03/11] dmaengine: dw-edma: Add per-channel interrupt routing control

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Message-ID: <aYOFEe-zyu4ZHTAl@lizhi-Precision-Tower-5810>
Date: Wed, 4 Feb 2026 12:42:41 -0500
From: Frank Li <Frank.li@....com>
To: Koichiro Den <den@...inux.co.jp>
Cc: vkoul@...nel.org, mani@...nel.org, jingoohan1@...il.com,
	lpieralisi@...nel.org, kwilczynski@...nel.org, robh@...nel.org,
	bhelgaas@...gle.com, dmaengine@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 03/11] dmaengine: dw-edma: Add per-channel interrupt
 routing control

On Wed, Feb 04, 2026 at 11:54:31PM +0900, Koichiro Den wrote:
> DesignWare EP eDMA can generate interrupts both locally and remotely
> (LIE/RIE). Remote eDMA users need to decide, per channel, whether
> completions should be handled locally, remotely, or both. Unless
> carefully configured, the endpoint and host would race to ack the
> interrupt.
>
> Introduce a dw_edma_peripheral_config that holds per-channel interrupt
> routing mode. Update v0 programming so that RIE and local done/abort
> interrupt masking follow the selected mode. The default mode keeps the
> original behavior, so unless the new peripheral_config is explicitly
> used and set, no functional changes.
>
> For now, HDMA is not supported for the peripheral_config. Until the
> support is implemented and validated, explicitly reject it for HDMA to
> avoid silently misconfiguring interrupt routing.
>
> Signed-off-by: Koichiro Den <den@...inux.co.jp>
> ---
>  drivers/dma/dw-edma/dw-edma-core.c    | 24 +++++++++++++++++++++++
>  drivers/dma/dw-edma/dw-edma-core.h    | 13 +++++++++++++
>  drivers/dma/dw-edma/dw-edma-v0-core.c | 26 +++++++++++++++++--------
>  include/linux/dma/edma.h              | 28 +++++++++++++++++++++++++++
>  4 files changed, 83 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index 38832d9447fd..b4cb02d545bd 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -224,6 +224,29 @@ static int dw_edma_device_config(struct dma_chan *dchan,
>  				 struct dma_slave_config *config)
>  {
>  	struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
> +	const struct dw_edma_peripheral_config *pcfg;
> +
> +	/* peripheral_config is optional, default keeps legacy behaviour. */
> +	chan->irq_mode = DW_EDMA_CH_IRQ_DEFAULT;
> +
> +	if (config->peripheral_config) {
> +		if (chan->dw->chip->mf == EDMA_MF_HDMA_NATIVE)
> +			return -EOPNOTSUPP;
> +
> +		if (config->peripheral_size < sizeof(*pcfg))
> +			return -EINVAL;

It is good to check here.

> +
> +		pcfg = config->peripheral_config;

save whole peripheral_config in case need more special peripheral
configuration in future.

> +		switch (pcfg->irq_mode) {
> +		case DW_EDMA_CH_IRQ_DEFAULT:
> +		case DW_EDMA_CH_IRQ_LOCAL:
> +		case DW_EDMA_CH_IRQ_REMOTE:
> +			chan->irq_mode = pcfg->irq_mode;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +	}

use helper function to get irq_mode. I posted combine config and prep by
one call.

https://lore.kernel.org/dmaengine/20260105-dma_prep_config-v3-0-a8480362fd42@nxp.com/

So we use such helper to get irq node after above patch merge. It is not
big deal, I can change it later. If provide helper funtions, it will be
slice better.

>
>  	memcpy(&chan->config, config, sizeof(*config));
>  	chan->configured = true;
> @@ -750,6 +773,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc)
>  		chan->configured = false;
>  		chan->request = EDMA_REQ_NONE;
>  		chan->status = EDMA_ST_IDLE;
> +		chan->irq_mode = DW_EDMA_CH_IRQ_DEFAULT;
>
>  		if (chan->dir == EDMA_DIR_WRITE)
>  			chan->ll_max = (chip->ll_region_wr[chan->id].sz / EDMA_LL_SZ);
...
>
> +/*
> + * enum dw_edma_ch_irq_mode - per-channel interrupt routing control
> + * @DW_EDMA_CH_IRQ_DEFAULT:   LIE=1/RIE=1, local interrupt unmasked
> + * @DW_EDMA_CH_IRQ_LOCAL:     LIE=1/RIE=0

keep consistent after "," for each enum

Frank

> + * @DW_EDMA_CH_IRQ_REMOTE:    LIE=1/RIE=1, local interrupt masked
> + *
> + * Some implementations require using LIE=1/RIE=1 with the local interrupt
> + * masked to generate a remote-only interrupt (rather than LIE=0/RIE=1).
> + * See the DesignWare endpoint databook 5.40, "Hint" below "Figure 8-22
> + * Write Interrupt Generation".
> + */
> +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_peripheral_config - dw-edma specific slave configuration
> + * @irq_mode: per-channel interrupt routing control.
> + *
> + * Pass this structure via dma_slave_config.peripheral_config and
> + * dma_slave_config.peripheral_size.
> + */
> +struct dw_edma_peripheral_config {
> +	enum dw_edma_ch_irq_mode irq_mode;
> +};
> +
>  /**
>   * struct dw_edma_chip - representation of DesignWare eDMA controller hardware
>   * @dev:		 struct device of the eDMA controller
> --
> 2.51.0
>