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Message-ID: <20260209062952.2049053-2-den@valinux.co.jp>
Date: Mon, 9 Feb 2026 15:29:44 +0900
From: Koichiro Den <den@...inux.co.jp>
To: vkoul@...nel.org,
mani@...nel.org,
Frank.Li@....com,
cassel@...nel.org,
jingoohan1@...il.com,
lpieralisi@...nel.org,
kwilczynski@...nel.org,
robh@...nel.org,
bhelgaas@...gle.com,
kishon@...nel.org,
jdmason@...zu.us,
allenbh@...il.com
Cc: dmaengine@...r.kernel.org,
linux-pci@...r.kernel.org,
ntb@...ts.linux.dev,
linux-kselftest@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v5 1/8] dmaengine: dw-edma: Deassert emulated interrupts in the IRQ handler
Some DesignWare eDMA instances support "interrupt emulation", where a
software write can assert the IRQ line without setting the normal
DONE/ABORT status bits.
With a shared IRQ handler the driver cannot reliably distinguish an
emulated interrupt from a real one by only looking at DONE/ABORT status
bits. Leaving the emulated IRQ asserted may leave a level-triggered IRQ
line permanently asserted.
Add a core callback, .ack_emulated_irq(), to perform the core-specific
deassert sequence and call it from the read/write/common IRQ handlers.
Note that previously a direct software write could assert the emulated
IRQ without DMA activity, leading to the interrupt never getting
deasserted. This patch resolves it.
For v0, a zero write to INT_CLEAR deasserts the emulated IRQ and is a
no-op for real interrupts. HDMA is not tested or verified and is
therefore unsupported for now.
Signed-off-by: Koichiro Den <den@...inux.co.jp>
---
drivers/dma/dw-edma/dw-edma-core.c | 48 ++++++++++++++++++++++++---
drivers/dma/dw-edma/dw-edma-core.h | 10 ++++++
drivers/dma/dw-edma/dw-edma-v0-core.c | 11 ++++++
3 files changed, 64 insertions(+), 5 deletions(-)
diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 8e5f7defa6b6..fe131abf1ca3 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -663,7 +663,24 @@ static void dw_edma_abort_interrupt(struct dw_edma_chan *chan)
chan->status = EDMA_ST_IDLE;
}
-static inline irqreturn_t dw_edma_interrupt_write(int irq, void *data)
+static inline irqreturn_t dw_edma_interrupt_emulated(void *data)
+{
+ struct dw_edma_irq *dw_irq = data;
+ struct dw_edma *dw = dw_irq->dw;
+
+ /*
+ * Interrupt emulation may assert the IRQ line without updating the
+ * normal DONE/ABORT status bits. With a shared IRQ handler we
+ * cannot reliably detect such events by status registers alone, so
+ * always perform the core-specific deassert sequence.
+ */
+ if (dw_edma_core_ack_emulated_irq(dw))
+ return IRQ_NONE;
+
+ return IRQ_HANDLED;
+}
+
+static inline irqreturn_t dw_edma_interrupt_write_inner(int irq, void *data)
{
struct dw_edma_irq *dw_irq = data;
@@ -672,7 +689,7 @@ static inline irqreturn_t dw_edma_interrupt_write(int irq, void *data)
dw_edma_abort_interrupt);
}
-static inline irqreturn_t dw_edma_interrupt_read(int irq, void *data)
+static inline irqreturn_t dw_edma_interrupt_read_inner(int irq, void *data)
{
struct dw_edma_irq *dw_irq = data;
@@ -681,12 +698,33 @@ static inline irqreturn_t dw_edma_interrupt_read(int irq, void *data)
dw_edma_abort_interrupt);
}
-static irqreturn_t dw_edma_interrupt_common(int irq, void *data)
+static inline irqreturn_t dw_edma_interrupt_write(int irq, void *data)
+{
+ irqreturn_t ret = IRQ_NONE;
+
+ ret |= dw_edma_interrupt_write_inner(irq, data);
+ ret |= dw_edma_interrupt_emulated(data);
+
+ return ret;
+}
+
+static inline irqreturn_t dw_edma_interrupt_read(int irq, void *data)
+{
+ irqreturn_t ret = IRQ_NONE;
+
+ ret |= dw_edma_interrupt_read_inner(irq, data);
+ ret |= dw_edma_interrupt_emulated(data);
+
+ return ret;
+}
+
+static inline irqreturn_t dw_edma_interrupt_common(int irq, void *data)
{
irqreturn_t ret = IRQ_NONE;
- ret |= dw_edma_interrupt_write(irq, data);
- ret |= dw_edma_interrupt_read(irq, data);
+ ret |= dw_edma_interrupt_write_inner(irq, data);
+ ret |= dw_edma_interrupt_read_inner(irq, data);
+ ret |= dw_edma_interrupt_emulated(data);
return ret;
}
diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
index 71894b9e0b15..50b87b63b581 100644
--- a/drivers/dma/dw-edma/dw-edma-core.h
+++ b/drivers/dma/dw-edma/dw-edma-core.h
@@ -126,6 +126,7 @@ struct dw_edma_core_ops {
void (*start)(struct dw_edma_chunk *chunk, bool first);
void (*ch_config)(struct dw_edma_chan *chan);
void (*debugfs_on)(struct dw_edma *dw);
+ void (*ack_emulated_irq)(struct dw_edma *dw);
};
struct dw_edma_sg {
@@ -206,4 +207,13 @@ void dw_edma_core_debugfs_on(struct dw_edma *dw)
dw->core->debugfs_on(dw);
}
+static inline int dw_edma_core_ack_emulated_irq(struct dw_edma *dw)
+{
+ if (!dw->core->ack_emulated_irq)
+ return -EOPNOTSUPP;
+
+ dw->core->ack_emulated_irq(dw);
+ return 0;
+}
+
#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..82b9c063c10f 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
@@ -509,6 +509,16 @@ static void dw_edma_v0_core_debugfs_on(struct dw_edma *dw)
dw_edma_v0_debugfs_on(dw);
}
+static void dw_edma_v0_core_ack_emulated_irq(struct dw_edma *dw)
+{
+ /*
+ * Interrupt emulation may assert the IRQ without setting
+ * DONE/ABORT status bits. A zero write to INT_CLEAR deasserts the
+ * emulated IRQ, while being a no-op for real interrupts.
+ */
+ SET_BOTH_32(dw, int_clear, 0);
+}
+
static const struct dw_edma_core_ops dw_edma_v0_core = {
.off = dw_edma_v0_core_off,
.ch_count = dw_edma_v0_core_ch_count,
@@ -517,6 +527,7 @@ static const struct dw_edma_core_ops dw_edma_v0_core = {
.start = dw_edma_v0_core_start,
.ch_config = dw_edma_v0_core_ch_config,
.debugfs_on = dw_edma_v0_core_debugfs_on,
+ .ack_emulated_irq = dw_edma_v0_core_ack_emulated_irq,
};
void dw_edma_v0_core_register(struct dw_edma *dw)
--
2.51.0
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