[PATCH V2 0/3] dmaengine: zynqmp_dma: Add per-channel reset support

[PATCH V2 0/3] dmaengine: zynqmp_dma: Add per-channel reset support

[Golla Nagendra]

This series adds per-channel reset support to the ZynqMP DMA driver using
the generic reset framework, along with the corresponding dt-bindings
update. It also adds a runtime PM guard in the IRQ handler to handle
spurious interrupts safely.

Patch 1 adds the optional 'resets' property to the ZynqMP DMA dt-binding.

Patch 2 adds reset control handling in the channel probe path to assert
and deassert the channel reset during initialization.

Patch 3 adds a pm_runtime_get_if_active() check in the IRQ handler to
avoid accessing hardware registers when the device is runtime-suspended,
which could occur on spurious interrupts.

Changes in V2:
- Added patch 3 to guard IRQ handler against spurious interrupts

Golla Nagendra (2):
  dmaengine: zynqmp_dma: Add per-channel reset support
  dmaengine: zynqmp_dma: Guard IRQ handler against spurious interrupts

Jay Buddhabhatti (1):
  dt-bindings: dma: xilinx: Add optional resets property for ZDMA

 .../bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml     |  3 +++
 drivers/dma/xilinx/zynqmp_dma.c                      | 12 ++++++++++++
 2 files changed, 15 insertions(+)

-- 
2.34.1

[PATCH V2 1/3] dt-bindings: dma: xilinx: Add optional resets property for ZDMA

[Golla Nagendra]

From: Jay Buddhabhatti <jay.buddhabhatti@amd.com>

Newer SoCs such as Versal Gen2 and Versal‑Net expose a reset line
for ZDMA. Older SoCs do not have this provision. Add an optional
resets property to describe this reset.

Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com>
Co-developed-by: Golla Nagendra <nagendra.golla@amd.com>
Signed-off-by: Golla Nagendra <nagendra.golla@amd.com>
---
 .../devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml    | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml b/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
index 2da86037ad79..dff16763e11b 100644
--- a/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
+++ b/Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dma-1.0.yaml
@@ -56,6 +56,9 @@ properties:
   iommus:
     maxItems: 1
 
+  resets:
+    maxItems: 1
+
   power-domains:
     maxItems: 1
 
-- 
2.34.1

[PATCH V2 2/3] dmaengine: zynqmp_dma: Add per-channel reset support

[Golla Nagendra]

Versal Gen 2 and Versal Net SoCs expose a dedicated reset line per
ZDMA channel, replacing the earlier approach where a single reset
was shared across all channels. Add reset handling in the channel
probe path using device_reset_optional() to trigger a reset pulse
on the channel during initialization.

Platforms without per-channel reset continue to work unaffected
since device_reset_optional() returns 0 when no reset is specified.

add pm_runtime_put_noidle() in the probe error path before
pm_runtime_disable() to balance the usage counter incremented by
pm_runtime_resume_and_get(). This is particularly important since
device_reset_optional() can return -EPROBE_DEFER, causing the
kernel to retry probe() and leak one PM usage count per retry
without the put.

Signed-off-by: Golla Nagendra <nagendra.golla@amd.com>
---
 drivers/dma/xilinx/zynqmp_dma.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
index f6a812e49ddc..a9dfec3c0ca3 100644
--- a/drivers/dma/xilinx/zynqmp_dma.c
+++ b/drivers/dma/xilinx/zynqmp_dma.c
@@ -18,6 +18,7 @@
 #include <linux/clk.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 
 #include "../dmaengine.h"
 
@@ -916,6 +917,11 @@ static int zynqmp_dma_chan_probe(struct zynqmp_dma_device *zdev,
 	if (IS_ERR(chan->regs))
 		return PTR_ERR(chan->regs);
 
+	err = device_reset_optional(&pdev->dev);
+	if (err)
+		return dev_err_probe(&pdev->dev, err,
+				     "failed to reset channel\n");
+
 	chan->bus_width = ZYNQMP_DMA_BUS_WIDTH_64;
 	chan->dst_burst_len = ZYNQMP_DMA_MAX_DST_BURST_LEN;
 	chan->src_burst_len = ZYNQMP_DMA_MAX_SRC_BURST_LEN;
@@ -1152,6 +1158,7 @@ static int zynqmp_dma_probe(struct platform_device *pdev)
 err_disable_pm:
 	if (!pm_runtime_enabled(zdev->dev))
 		zynqmp_dma_runtime_suspend(zdev->dev);
+	pm_runtime_put_noidle(zdev->dev);
 	pm_runtime_disable(zdev->dev);
 	return ret;
 }
-- 
2.34.1

[PATCH V2 3/3] dmaengine: zynqmp_dma: Guard IRQ handler against spurious interrupts

[Golla Nagendra]

Add pm_runtime_get_if_active() check in zynqmp_dma_irq_handler() to
safely handle spurious interrupts that may arrive while the device is
runtime-suspended. Without this guard, a spurious interrupt could cause
the handler to access hardware registers (ISR, IMR) with clocks gated,
potentially leading to a synchronous external abort and kernel crash.

When the device is not runtime-active, pm_runtime_get_if_active()
returns false without incrementing the usage counter, and the handler
returns IRQ_NONE immediately. When the device is active, it increments
the usage counter to prevent a concurrent runtime suspend during
register access, and pm_runtime_put() releases the reference afterward.

Signed-off-by: Golla Nagendra <nagendra.golla@amd.com>
---
 drivers/dma/xilinx/zynqmp_dma.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
index a9dfec3c0ca3..ce9163138be7 100644
--- a/drivers/dma/xilinx/zynqmp_dma.c
+++ b/drivers/dma/xilinx/zynqmp_dma.c
@@ -730,6 +730,9 @@ static irqreturn_t zynqmp_dma_irq_handler(int irq, void *data)
 	u32 isr, imr, status;
 	irqreturn_t ret = IRQ_NONE;
 
+	if (pm_runtime_get_if_active(chan->dev) <= 0)
+		return IRQ_NONE;
+
 	isr = readl(chan->regs + ZYNQMP_DMA_ISR);
 	imr = readl(chan->regs + ZYNQMP_DMA_IMR);
 	status = isr & ~imr;
@@ -756,6 +759,8 @@ static irqreturn_t zynqmp_dma_irq_handler(int irq, void *data)
 		ret = IRQ_HANDLED;
 	}
 
+	pm_runtime_put(chan->dev);
+
 	return ret;
 }
 
-- 
2.34.1

Re: [PATCH V2 2/3] dmaengine: zynqmp_dma: Add per-channel reset support

[Frank Li]

On Thu, Jun 18, 2026 at 12:40:55PM +0530, Golla Nagendra wrote:
> [You don't often get email from nagendra.golla@amd.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> Versal Gen 2 and Versal Net SoCs expose a dedicated reset line per
> ZDMA channel, replacing the earlier approach where a single reset
> was shared across all channels. Add reset handling in the channel
> probe path using device_reset_optional() to trigger a reset pulse
> on the channel during initialization.
>
> Platforms without per-channel reset continue to work unaffected
> since device_reset_optional() returns 0 when no reset is specified.
>
> add pm_runtime_put_noidle() in the probe error path before
> pm_runtime_disable() to balance the usage counter incremented by
> pm_runtime_resume_and_get(). This is particularly important since
> device_reset_optional() can return -EPROBE_DEFER, causing the
> kernel to retry probe() and leak one PM usage count per retry
> without the put.

Use sperate patch to fix this problem

Frank
>
> Signed-off-by: Golla Nagendra <nagendra.golla@amd.com>
> ---
>  drivers/dma/xilinx/zynqmp_dma.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
> index f6a812e49ddc..a9dfec3c0ca3 100644
> --- a/drivers/dma/xilinx/zynqmp_dma.c
> +++ b/drivers/dma/xilinx/zynqmp_dma.c
> @@ -18,6 +18,7 @@
>  #include <linux/clk.h>
>  #include <linux/io-64-nonatomic-lo-hi.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/reset.h>
>
>  #include "../dmaengine.h"
>
> @@ -916,6 +917,11 @@ static int zynqmp_dma_chan_probe(struct zynqmp_dma_device *zdev,
>         if (IS_ERR(chan->regs))
>                 return PTR_ERR(chan->regs);
>
> +       err = device_reset_optional(&pdev->dev);
> +       if (err)
> +               return dev_err_probe(&pdev->dev, err,
> +                                    "failed to reset channel\n");
> +
>         chan->bus_width = ZYNQMP_DMA_BUS_WIDTH_64;
>         chan->dst_burst_len = ZYNQMP_DMA_MAX_DST_BURST_LEN;
>         chan->src_burst_len = ZYNQMP_DMA_MAX_SRC_BURST_LEN;
> @@ -1152,6 +1158,7 @@ static int zynqmp_dma_probe(struct platform_device *pdev)
>  err_disable_pm:
>         if (!pm_runtime_enabled(zdev->dev))
>                 zynqmp_dma_runtime_suspend(zdev->dev);
> +       pm_runtime_put_noidle(zdev->dev);
>         pm_runtime_disable(zdev->dev);
>         return ret;
>  }
> --
> 2.34.1
>

Re: [PATCH V2 3/3] dmaengine: zynqmp_dma: Guard IRQ handler against spurious interrupts

[Frank Li]

On Thu, Jun 18, 2026 at 12:40:56PM +0530, Golla Nagendra wrote:
> [You don't often get email from nagendra.golla@amd.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> Add pm_runtime_get_if_active() check in zynqmp_dma_irq_handler() to
> safely handle spurious interrupts that may arrive while the device is
> runtime-suspended. Without this guard, a spurious interrupt could cause
> the handler to access hardware registers (ISR, IMR) with clocks gated,
> potentially leading to a synchronous external abort and kernel crash.
>
> When the device is not runtime-active, pm_runtime_get_if_active()
> returns false without incrementing the usage counter, and the handler
> returns IRQ_NONE immediately. When the device is active, it increments
> the usage counter to prevent a concurrent runtime suspend during
> register access, and pm_runtime_put() releases the reference afterward.
>
> Signed-off-by: Golla Nagendra <nagendra.golla@amd.com>
> ---
>  drivers/dma/xilinx/zynqmp_dma.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
> index a9dfec3c0ca3..ce9163138be7 100644
> --- a/drivers/dma/xilinx/zynqmp_dma.c
> +++ b/drivers/dma/xilinx/zynqmp_dma.c
> @@ -730,6 +730,9 @@ static irqreturn_t zynqmp_dma_irq_handler(int irq, void *data)
>         u32 isr, imr, status;
>         irqreturn_t ret = IRQ_NONE;
>
> +       if (pm_runtime_get_if_active(chan->dev) <= 0)
> +               return IRQ_NONE;
> +

Can you add AQUIRE macro in include/linux/pm_runtime.h
so here can use PM_RUNTIME_ACQUIRE_IF_ACITVE

Other person can get benefit for auto clean up especially if there are some
difference return path.

Frank

>         isr = readl(chan->regs + ZYNQMP_DMA_ISR);
>         imr = readl(chan->regs + ZYNQMP_DMA_IMR);
>         status = isr & ~imr;
> @@ -756,6 +759,8 @@ static irqreturn_t zynqmp_dma_irq_handler(int irq, void *data)
>                 ret = IRQ_HANDLED;
>         }
>
> +       pm_runtime_put(chan->dev);
> +
>         return ret;
>  }
>
> --
> 2.34.1
>