On Fri, Feb 06, 2026 at 12:43:54PM -0500, Frank Li wrote:
> On Sat, Feb 07, 2026 at 02:26:38AM +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 <[email protected]>
> > ---
> > drivers/dma/dw-edma/dw-edma-core.c | 37 +++++++++++++++++++++++++++
> > 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, 96 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/dma/dw-edma/dw-edma-core.c
> > b/drivers/dma/dw-edma/dw-edma-core.c
> > index 8e5f7defa6b6..0c3461f9174a 100644
> > --- a/drivers/dma/dw-edma/dw-edma-core.c
> > +++ b/drivers/dma/dw-edma/dw-edma-core.c
> > @@ -219,11 +219,47 @@ static void dw_edma_device_caps(struct dma_chan
> > *dchan,
> > }
> > }
> >
> > +static int dw_edma_parse_irq_mode(struct dw_edma_chan *chan,
> > + const struct dma_slave_config *config,
> > + enum dw_edma_ch_irq_mode *mode)
> > +{
> > + const struct dw_edma_peripheral_config *pcfg;
> > +
> > + /* peripheral_config is optional, default keeps legacy behaviour. */
> > + *mode = DW_EDMA_CH_IRQ_DEFAULT;
> > + if (!config || !config->peripheral_config)
> > + return 0;
> > +
> > + if (chan->dw->chip->mf == EDMA_MF_HDMA_NATIVE)
> > + return -EOPNOTSUPP;
> > +
> > + if (config->peripheral_size < sizeof(*pcfg))
> > + return -EINVAL;
> > +
> > + pcfg = config->peripheral_config;
> > + switch (pcfg->irq_mode) {
> > + case DW_EDMA_CH_IRQ_DEFAULT:
> > + case DW_EDMA_CH_IRQ_LOCAL:
> > + case DW_EDMA_CH_IRQ_REMOTE:
> > + *mode = pcfg->irq_mode;
> > + return 0;
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +
> > static int dw_edma_device_config(struct dma_chan *dchan,
> > struct dma_slave_config *config)
> > {
> > struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
> > + enum dw_edma_ch_irq_mode mode;
> > + int ret;
> > +
> > + ret = dw_edma_parse_irq_mode(chan, config, &mode);
> > + if (ret)
> > + return ret;
> >
> > + chan->irq_mode = mode;
> > memcpy(&chan->config, config, sizeof(*config));
> > chan->configured = true;
> >
> > @@ -749,6 +785,7 @@ 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);
> > diff --git a/drivers/dma/dw-edma/dw-edma-core.h
> > b/drivers/dma/dw-edma/dw-edma-core.h
> > index 71894b9e0b15..0608b9044a08 100644
> > --- a/drivers/dma/dw-edma/dw-edma-core.h
> > +++ b/drivers/dma/dw-edma/dw-edma-core.h
> > @@ -81,6 +81,8 @@ struct dw_edma_chan {
> >
> > struct msi_msg msi;
> >
> > + enum dw_edma_ch_irq_mode irq_mode;
> > +
> > enum dw_edma_request request;
> > enum dw_edma_status status;
> > u8 configured;
> > @@ -206,4 +208,15 @@ void dw_edma_core_debugfs_on(struct dw_edma *dw)
> > dw->core->debugfs_on(dw);
> > }
> >
> > +static inline
> > +bool dw_edma_core_ch_ignore_irq(struct dw_edma_chan *chan)
>
> nit:
>
> static inline bool
> dw_edma_core_ch_ignore_irq()
Thanks for the nit. I followed the style of the neighboring codes, but I
agree it's better on its own. Let me fix that in the next revision.
>
> > +{
> > + struct dw_edma *dw = chan->dw;
> > +
> > + if (dw->chip->flags & DW_EDMA_CHIP_LOCAL)
> > + 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 b75fdaffad9a..a0441e8aa3b3 100644
> > --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> > +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> > @@ -256,8 +256,10 @@ 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];
> >
> > - dw_edma_v0_core_clear_done_int(chan);
> > - done(chan);
> > + if (!dw_edma_core_ch_ignore_irq(chan)) {
> > + dw_edma_v0_core_clear_done_int(chan);
> > + done(chan);
> > + }
> >
> > ret = IRQ_HANDLED;
> > }
> > @@ -267,8 +269,10 @@ 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];
> >
> > - dw_edma_v0_core_clear_abort_int(chan);
> > - abort(chan);
> > + if (!dw_edma_core_ch_ignore_irq(chan)) {
> > + 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 3080747689f6..53b31a974331 100644
> > --- a/include/linux/dma/edma.h
> > +++ b/include/linux/dma/edma.h
> > @@ -60,6 +60,34 @@ 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: LIE=1/RIE=1, local interrupt unmasked
> > + * @DW_EDMA_CH_IRQ_LOCAL: LIE=1/RIE=0, local interrupt unmasked
> > + * @DW_EDMA_CH_IRQ_REMOTE: LIE=1/RIE=1, local interrupt masked
>
> You'd better descript remote interrupt also.
Thanks for the comment. Hm, while revisiting this I noticed the current
enum comment is overly LIE/RIE-specific and can even be misleading (e.g.
*_IRQ_DEFAULT does not imply a RIE=1 behavior when the eDMA instance is
operated purely in a local-only setup).
I think it’s clearer to describe the modes in terms of behavior and add a
short explanation of what each mode means outside the individual field
descriptions. Below is a draft of the updated kernel-doc comment. How does
this look to you?
/**
* enum dw_edma_ch_irq_mode - per-channel interrupt routing control
* @DW_EDMA_CH_IRQ_DEFAULT: Keep legacy behavior.
* @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.
*
* 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,
};
Also, for v5 I think I can drop this patch 1/9 to keep the series minimal
and focused on the doorbell fallback implementation (and its testing). I
can repost this patch later together with the actual consumer. Please let
me know if you have any objections.
If you're ok with the updated comment above, I believe it should also be
fine to keep your Reviewed-by tag on the repost.
Thanks for the review,
Koichiro
>
> Reviewed-by: Frank Li <[email protected]>
> > + *
> > + * 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
> >
