[PATCH v4 02/14] dmaengine: dw-edma: Add per-channel interrupt routing control
From: Koichiro Den
Date: Fri Jul 10 2026 - 04:21:56 EST
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 channel interrupt routing state and initialize it from the
controller instance configuration. Update the v0 eDMA and HDMA native
paths so linked-list interrupt generation, HDMA non-linked-list
interrupt enables, and DONE/ABORT masking follow the selected mode. For
HDMA native non-linked-list channels, use the dedicated remote
stop/abort enables without local stop/abort enables.
Keep the existing dw-edma-pcie host-side instances in remote interrupt
routing mode so their IMWr/MSI completion model remains unchanged after
local routing becomes the zero value.
Note:
- The routing mode describes where a channel should report completion.
It does not by itself say whether this dw-edma instance owns the
interrupt status. A local instance must ignore remote-only channels,
and a remote instance must ignore local-only channels, even if such
interrupts are unexpectedly delivered. Otherwise the non-owner side
could steal the interrupt from the owner by clearing shared DONE/ABORT
status.
- This drops the stop/abort interrupt masking that non-LL setup has
applied since its introduction commit b7560798466a ("dmaengine:
dw-edma: Add non-LL mode"). The databook's non-LL examples program the
masks to zero in both directions, and with the local enables now
cleared in remote mode there is no local interrupt left to mask.
Remote-driven non-LL users keep the same delivered interrupts: the
local pin was enabled-but-masked before and is not enabled at all now.
Cc: Devendra K Verma <devendra.verma@xxxxxxx>
Suggested-by: Frank Li <Frank.Li@xxxxxxx>
Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
Changes in v4:
- Document that a local instance never drives a remote-routed channel
as the channel is handed over to and programmed by the remote side.
(Sashiko)
- Rename dw_edma_get_irq_mode() back to dw_edma_get_default_irq_mode()
and simplify its implementation. (Frank)
- Drop redundant dw_edma_get_irq_mode() call from
dw_edma_alloc_chan_resources(). (Frank)
- Drop unnecessary new-line drops. (Frank)
- Simplify by just using DW_EDMA_CH_IRQ_REMOTE instead. (Frank)
- Drop unnecessary chip->irq_mode. (Frank)
- Revise int_setup for HDMA.
drivers/dma/dw-edma/dw-edma-core.c | 10 ++++++++
drivers/dma/dw-edma/dw-edma-core.h | 13 +++++++++++
drivers/dma/dw-edma/dw-edma-v0-core.c | 28 +++++++++++++++++++----
drivers/dma/dw-edma/dw-hdma-v0-core.c | 28 +++++++++++++++--------
include/linux/dma/edma.h | 33 +++++++++++++++++++++++++++
5 files changed, 99 insertions(+), 13 deletions(-)
diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 704d8f9746e8..1c6db2c381e2 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -255,6 +255,15 @@ static void dw_edma_device_caps(struct dma_chan *dchan,
}
}
+static enum dw_edma_ch_irq_mode
+dw_edma_get_default_irq_mode(struct dw_edma_chan *chan)
+{
+ struct dw_edma_chip *chip = chan->dw->chip;
+
+ return chip->flags & DW_EDMA_CHIP_LOCAL ? DW_EDMA_CH_IRQ_LOCAL :
+ DW_EDMA_CH_IRQ_REMOTE;
+}
+
static int dw_edma_device_config(struct dma_chan *dchan,
struct dma_slave_config *config)
{
@@ -1016,6 +1025,7 @@ 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_get_default_irq_mode(chan);
INIT_WORK(&chan->irq_work, dw_edma_irq_work);
atomic_set(&chan->irq_pending, 0);
diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
index a6a9ed09fe1b..3ea384706b1b 100644
--- a/drivers/dma/dw-edma/dw-edma-core.h
+++ b/drivers/dma/dw-edma/dw-edma-core.h
@@ -83,6 +83,8 @@ 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;
@@ -236,4 +238,15 @@ dw_edma_core_db_offset(struct dw_edma *dw)
return dw->core->db_offset(dw);
}
+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)
+ 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 377812eaa110..14700ac42fa8 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
@@ -254,6 +254,9 @@ 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 (unlikely(dw_edma_core_ch_ignore_irq(chan)))
+ continue;
+
dw_edma_v0_core_clear_done_int(chan);
done(chan);
@@ -265,6 +268,9 @@ 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 (unlikely(dw_edma_core_ch_ignore_irq(chan)))
+ continue;
+
dw_edma_v0_core_clear_abort_int(chan);
abort(chan);
@@ -329,7 +335,16 @@ 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))
+
+ /*
+ * A local instance never issues transfers on a
+ * remote-routed channel: on CHIP_LOCAL instances,
+ * REMOTE routing denotes a channel handed over to the
+ * remote side, which programs the linked list through
+ * its own instance.
+ */
+ if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) &&
+ chan->irq_mode == DW_EDMA_CH_IRQ_REMOTE)
control |= DW_EDMA_V0_RIE;
}
@@ -406,12 +421,17 @@ static void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
break;
}
}
- /* Interrupt unmask - done, abort */
+ /* Interrupt mask/unmask - done, abort */
raw_spin_lock_irqsave(&dw->lock, flags);
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/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
index 44e7b6c1263c..cc908ca24061 100644
--- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
@@ -52,17 +52,25 @@ __dw_ch_regs(struct dw_edma *dw, enum dw_edma_dir dir, u16 ch)
/* HDMA management callbacks */
static u32 dw_hdma_v0_core_int_setup(struct dw_edma_chan *chan, u32 val)
{
- if (chan->non_ll)
- val |= HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK;
- else
- val &= ~(HDMA_V0_STOP_INT_MASK | HDMA_V0_ABORT_INT_MASK);
+ val &= ~(HDMA_V0_LOCAL_ABORT_INT_EN | HDMA_V0_REMOTE_ABORT_INT_EN |
+ HDMA_V0_LOCAL_STOP_INT_EN | HDMA_V0_REMOTE_STOP_INT_EN |
+ HDMA_V0_ABORT_INT_MASK | HDMA_V0_STOP_INT_MASK);
- val |= HDMA_V0_LOCAL_STOP_INT_EN | HDMA_V0_LOCAL_ABORT_INT_EN;
- if (!(chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL))
- val |= HDMA_V0_REMOTE_STOP_INT_EN |
- HDMA_V0_REMOTE_ABORT_INT_EN;
+ /*
+ * DWC PCIe DM Databook 6.10a-lca06 remote non-LL examples
+ * program LSIE/LAIE=0 and RSIE/RAIE=1. Use the HDMA remote
+ * enable bits directly for stop/abort routing.
+ *
+ * This is unlike the eDMA LIE/RIE and HDMA LL LWIE/RWIE paths:
+ * those pair local and remote enables and mask the local interrupt
+ * path, but HDMA stop/abort has separate remote enable bits.
+ */
+ if (chan->irq_mode == DW_EDMA_CH_IRQ_REMOTE)
+ return val | HDMA_V0_REMOTE_ABORT_INT_EN |
+ HDMA_V0_REMOTE_STOP_INT_EN;
- return val;
+ return val | HDMA_V0_LOCAL_ABORT_INT_EN |
+ HDMA_V0_LOCAL_STOP_INT_EN;
}
static void dw_hdma_v0_core_off(struct dw_edma *dw)
@@ -147,6 +155,8 @@ dw_hdma_v0_core_handle_int(struct dw_edma_irq *dw_irq, enum dw_edma_dir dir,
for_each_set_bit(pos, &mask, total) {
chan = &dw->chan[pos + off];
+ if (unlikely(dw_edma_core_ch_ignore_irq(chan)))
+ continue;
val = dw_hdma_v0_core_status_int(chan);
if (FIELD_GET(HDMA_V0_STOP_INT_MASK, val)) {
diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
index 1fafd5b0e315..1007122d4123 100644
--- a/include/linux/dma/edma.h
+++ b/include/linux/dma/edma.h
@@ -60,6 +60,39 @@ 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_LOCAL: local interrupt only (edma_int[])
+ * @DW_EDMA_CH_IRQ_REMOTE: remote interrupt only (IMWr/MSI), without
+ * delivering local edma_int[].
+ *
+ * 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 linked-list 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. See the
+ * DesignWare endpoint databook 6.30a, Linked List Mode interrupt handling
+ * ("Software Programming of an Endpoint's LIE and RIE Bits for Linked List
+ * Transfers", Attention).
+ *
+ * A local (DW_EDMA_CHIP_LOCAL) instance never issues transfers on a
+ * remote-routed channel: REMOTE routing on such an instance denotes a channel
+ * handed over to and driven by the remote side, and the recipe above is
+ * applied by the driving instance.
+ *
+ * HDMA linked-list watermark interrupts have the same LWIE/RWIE guidance. HDMA
+ * non-linked-list mode has dedicated local and remote stop/abort interrupt
+ * enables, and the remote CPU programming examples use remote enables without
+ * local enables.
+ */
+enum dw_edma_ch_irq_mode {
+ DW_EDMA_CH_IRQ_LOCAL = 0,
+ DW_EDMA_CH_IRQ_REMOTE,
+};
+
/**
* struct dw_edma_chip - representation of DesignWare eDMA controller hardware
* @dev: struct device of the eDMA controller
--
2.51.0