Re: [PATCH v4 2/3] dma: arm-dma350: support combined IRQ mode with runtime IRQ topology detection
From: Robin Murphy
Date: Tue Mar 24 2026 - 09:07:19 EST
On 2026-03-23 11:48 am, Jun Guo wrote:
DMA-350 can be integrated with either per-channel IRQ lines or a single
combined IRQ line. Add support for both layouts in a unified way.
Detect IRQ topology at probe time via platform_irq_count(), then:
- request one global IRQ and enable DMANSECCTRL.INTREN_ANYCHINTR for
combined mode, or
- request per-channel IRQs for channel mode.
Refactor IRQ completion/error handling into a shared channel handler
used by both global and per-channel IRQ paths, and guard against IRQs
arriving without an active descriptor.
Assisted-by: Cursor: GPT-5.3-Codex
Signed-off-by: Jun Guo <jun.guo@xxxxxxxxxxx>
---
drivers/dma/arm-dma350.c | 165 +++++++++++++++++++++++++++++++++------
1 file changed, 139 insertions(+), 26 deletions(-)
diff --git a/drivers/dma/arm-dma350.c b/drivers/dma/arm-dma350.c
index 84220fa83029..2cf6f783b44f 100644
--- a/drivers/dma/arm-dma350.c
+++ b/drivers/dma/arm-dma350.c
@@ -14,6 +14,7 @@
#include "virt-dma.h"
#define DMAINFO 0x0f00
+#define DRIVER_NAME "arm-dma350"
Why is this here in the middle of register definitions? But frankly why is it being added at all?
#define DMA_BUILDCFG0 0xb0
#define DMA_CFG_DATA_WIDTH GENMASK(18, 16)
@@ -142,6 +143,9 @@
#define LINK_LINKADDR BIT(30)
#define LINK_LINKADDRHI BIT(31)
+/* DMA NONSECURE CONTROL REGISTER */
+#define DMANSECCTRL 0x20c
Please follow the existing code rather than making a confusing ugly mess. DMANSECCTRL is a register frame at offset 0x0200; it contains (among others) a register named NSEC_CTRL at offset 0x0c.
+#define INTREN_ANYCHINTR_EN BIT(0)
enum ch_ctrl_donetype {
CH_CTRL_DONETYPE_NONE = 0,
@@ -192,6 +196,7 @@ struct d350_chan {
struct d350 {
struct dma_device dma;
+ void __iomem *base;
Why?
int nchan;
int nreq;
struct d350_chan channels[] __counted_by(nchan);
@@ -461,18 +466,40 @@ static void d350_issue_pending(struct dma_chan *chan)
spin_unlock_irqrestore(&dch->vc.lock, flags);
}
-static irqreturn_t d350_irq(int irq, void *data)
+static void d350_handle_chan_irq(struct d350_chan *dch, struct device *dev,
+ int chan_id, u32 ch_status)
{
- struct d350_chan *dch = data;
- struct device *dev = dch->vc.chan.device->dev;
- struct virt_dma_desc *vd = &dch->desc->vd;
- u32 ch_status;
+ struct virt_dma_desc *vd;
+ bool intr_done = ch_status & CH_STAT_INTR_DONE;
+ bool intr_err = ch_status & CH_STAT_INTR_ERR;
- ch_status = readl(dch->base + CH_STATUS);
- if (!ch_status)
- return IRQ_NONE;
+ if (!intr_done && !intr_err) {
Why is the logic being changed here?
+ if (chan_id >= 0)
+ dev_warn(dev, "Channel %d unexpected IRQ: 0x%08x\n",
+ chan_id, ch_status);
Why? I see no reason why "dev" shouldn't still be the channel device.
+ else
+ dev_warn(dev, "Unexpected IRQ source? 0x%08x\n", ch_status);
+ writel_relaxed(ch_status, dch->base + CH_STATUS);
+ return;
+ }
+
+ writel_relaxed(ch_status, dch->base + CH_STATUS);
+
+ spin_lock(&dch->vc.lock);
+ if (!dch->desc) {
+ if (chan_id >= 0)
+ dev_warn(dev,
+ "Channel %d IRQ without active descriptor: 0x%08x\n",
+ chan_id, ch_status);
+ else
+ dev_warn(dev, "IRQ without active descriptor: 0x%08x\n",
+ ch_status);
+ spin_unlock(&dch->vc.lock);
+ return;
+ }
This seems entirely new and nothing to do with refactoring. Why do you think it's necessary?
- if (ch_status & CH_STAT_INTR_ERR) {
+ vd = &dch->desc->vd;
+ if (intr_err) {
u32 errinfo = readl_relaxed(dch->base + CH_ERRINFO);
if (errinfo & (CH_ERRINFO_AXIRDPOISERR | CH_ERRINFO_AXIRDRESPERR))
@@ -483,14 +510,10 @@ static irqreturn_t d350_irq(int irq, void *data)
vd->tx_result.result = DMA_TRANS_ABORTED;
vd->tx_result.residue = d350_get_residue(dch);
- } else if (!(ch_status & CH_STAT_INTR_DONE)) {
- dev_warn(dev, "Unexpected IRQ source? 0x%08x\n", ch_status);
}
- writel_relaxed(ch_status, dch->base + CH_STATUS);
- spin_lock(&dch->vc.lock);
I can't recall the details off-hand right now, but I have a strong feeling the order of operations here was reasonably significant - what's the justifcation for changing it?
vchan_cookie_complete(vd);
- if (ch_status & CH_STAT_INTR_DONE) {
+ if (intr_done) {
dch->status = DMA_COMPLETE;
dch->residue = 0;
d350_start_next(dch);
@@ -499,6 +522,44 @@ static irqreturn_t d350_irq(int irq, void *data)
dch->residue = vd->tx_result.residue;
}
spin_unlock(&dch->vc.lock);
+}
+
+static irqreturn_t d350_global_irq(int irq, void *data)
+{
+ struct d350 *dmac = (struct d350 *)data;
This isn't C++
+ irqreturn_t ret = IRQ_NONE;
+ int i;
+
+ (void)irq;
Why?
+ for (i = 0; i < dmac->nchan; i++) {
+ struct d350_chan *dch = &dmac->channels[i];
+ u32 ch_status;
+
+ ch_status = readl(dch->base + CH_STATUS);
+ if (!ch_status)
Why is this factored out, only to be duplicated in both callers?
+ continue;
+
+ ret = IRQ_HANDLED;
+ d350_handle_chan_irq(dch, dmac->dma.dev, i, ch_status);
+ }
+
+ return ret;
+}
+
+static irqreturn_t d350_channel_irq(int irq, void *data)
+{
+ struct d350_chan *dch = data;
+ struct device *dev = dch->vc.chan.device->dev;
+ u32 ch_status;
+
+ (void)irq;
+
+ ch_status = readl(dch->base + CH_STATUS);
+ if (!ch_status)
+ return IRQ_NONE;
+
+ d350_handle_chan_irq(dch, dev, -1, ch_status);
return IRQ_HANDLED;
}
@@ -506,10 +567,18 @@ static irqreturn_t d350_irq(int irq, void *data)
static int d350_alloc_chan_resources(struct dma_chan *chan)
{
struct d350_chan *dch = to_d350_chan(chan);
- int ret = request_irq(dch->irq, d350_irq, IRQF_SHARED,
- dev_name(&dch->vc.chan.dev->device), dch);
- if (!ret)
- writel_relaxed(CH_INTREN_DONE | CH_INTREN_ERR, dch->base + CH_INTREN);
+ int ret = 0;
+
+ if (dch->irq >= 0) {
+ ret = request_irq(dch->irq, d350_channel_irq, IRQF_SHARED,
+ dev_name(&dch->vc.chan.dev->device), dch);
+ if (ret) {
+ dev_err(chan->device->dev, "Failed to request IRQ %d\n", dch->irq);
+ return ret;
+ }
+ }
+
+ writel_relaxed(CH_INTREN_DONE | CH_INTREN_ERR, dch->base + CH_INTREN);
return ret;
}
@@ -519,18 +588,21 @@ static void d350_free_chan_resources(struct dma_chan *chan)
struct d350_chan *dch = to_d350_chan(chan);
writel_relaxed(0, dch->base + CH_INTREN);
- free_irq(dch->irq, dch);
+ if (dch->irq >= 0) {
+ free_irq(dch->irq, dch);
+ dch->irq = -EINVAL;
+ }
vchan_free_chan_resources(&dch->vc);
}
static int d350_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
- struct d350 *dmac;
+ struct d350 *dmac = NULL;
Why?
void __iomem *base;
u32 reg;
- int ret, nchan, dw, aw, r, p;
- bool coherent, memset;
+ int ret, nchan, dw, aw, r, p, irq_count;
+ bool coherent, memset, combined_irq;
base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(base))
@@ -556,6 +628,7 @@ static int d350_probe(struct platform_device *pdev)
return -ENOMEM;
dmac->nchan = nchan;
+ dmac->base = base;
reg = readl_relaxed(base + DMAINFO + DMA_BUILDCFG1);
dmac->nreq = FIELD_GET(DMA_CFG_NUM_TRIGGER_IN, reg);
@@ -582,12 +655,46 @@ static int d350_probe(struct platform_device *pdev)
dmac->dma.device_issue_pending = d350_issue_pending;
INIT_LIST_HEAD(&dmac->dma.channels);
+ irq_count = platform_irq_count(pdev);
+ if (irq_count < 0)
+ return dev_err_probe(dev, irq_count,
+ "Failed to count interrupts\n");
+
+ if (irq_count == 1) {
+ combined_irq = true;
What if there's only 1 channel and it is actually using its dedicated IRQ?
+ } else if (irq_count >= nchan) {
+ combined_irq = false;
+ } else {
+ return dev_err_probe(dev, -EINVAL,
+ "Invalid IRQ count %d for %d channels\n",
+ irq_count, nchan);
Thsi is a change in behaviour, since we wouldm't currently consider it an error if the last 1 or more channels don't have an interrupt, but aren't accessible anyway - if a system *always* reserved the last couple of channels for the Secure world, arguably there would be no real requiremnt to describe them in the Non-Secure DT at all.
+ }
+
+ if (combined_irq) {
+ int host_irq = platform_get_irq(pdev, 0);
+
+ if (host_irq < 0)
+ return dev_err_probe(dev, host_irq,
+ "Failed to get IRQ\n");
+
+ ret = devm_request_irq(&pdev->dev, host_irq, d350_global_irq,
+ IRQF_SHARED, DRIVER_NAME, dmac);
+ if (ret)
+ return dev_err_probe(
+ dev, ret,
+ "Failed to request the combined IRQ %d\n",
+ host_irq);
+ /* Combined Non-Secure Channel Interrupt Enable */
+ writel_relaxed(INTREN_ANYCHINTR_EN, dmac->base + DMANSECCTRL);
+ }
+
/* Would be nice to have per-channel caps for this... */
memset = true;
for (int i = 0; i < nchan; i++) {
struct d350_chan *dch = &dmac->channels[i];
dch->base = base + DMACH(i);
+ dch->irq = -EINVAL;
writel_relaxed(CH_CMD_CLEAR, dch->base + CH_CMD);
reg = readl_relaxed(dch->base + CH_BUILDCFG1);
@@ -595,10 +702,15 @@ static int d350_probe(struct platform_device *pdev)
dev_warn(dev, "No command link support on channel %d\n", i);
continue;
}
- dch->irq = platform_get_irq(pdev, i);
- if (dch->irq < 0)
- return dev_err_probe(dev, dch->irq,
- "Failed to get IRQ for channel %d\n", i);
+
+ if (!combined_irq) {
+ dch->irq = platform_get_irq(pdev, i);
But here's the thing - even if we *were* to do something special in the DT binding, why not simply have:
if (combined_irq)
dch->irq = combined_irq_num;
else
dch->irq = platform_get_irq(pdev, i);
at this point, and then let everything else keep working the way it already does?
Thanks,
Robin.
+ if (dch->irq < 0)
+ return dev_err_probe(
+ dev, dch->irq,
+ "Failed to get IRQ for channel %d\n",
+ i);
+ }
dch->has_wrap = FIELD_GET(CH_CFG_HAS_WRAP, reg);
dch->has_trig = FIELD_GET(CH_CFG_HAS_TRIGIN, reg) &
@@ -640,6 +752,7 @@ static void d350_remove(struct platform_device *pdev)
}
static const struct of_device_id d350_of_match[] __maybe_unused = {
+ { .compatible = "cix,sky1-dma-350" },
{ .compatible = "arm,dma-350" },
{}
};