[PATCH v3 0/5] of/irq: Misc msi-parent handling fixes/clean-ups

[PATCH v3 0/5] of/irq: Misc msi-parent handling fixes/clean-ups

[Lorenzo Pieralisi]

This is series is a follow up to [1] - with additional patches that are
addressing Rob's feedback (pcie-layerscape-gen4 was removed from the
kernel, Yay !) and other bits and bobs I noticed while staring at the code.

Patch (1) is a fix and technically we would like to get it in v6.18 please.

Patch (4) is compile-tested only, I can not run it on HW, I do not have it,
Scott, Ray please test it if you can.

v2 -> v3:
	- Added additional patch to export of_msi_xlate()
	- Merged Marc's ITS parent diff
	- Added trailers, fixed commit logs

v2: https://lore.kernel.org/lkml/20251014095845.1310624-1-lpieralisi@kernel.org/
v1: https://lore.kernel.org/lkml/20250916091858.257868-1-lpieralisi@kernel.org/

[1] https://lore.kernel.org/lkml/20250916091858.257868-1-lpieralisi@kernel.org/

Cc: Sascha Bischoff <sascha.bischoff@arm.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Frank Li <Frank.Li@nxp.com>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: "Krzysztof Wilczyński" <kwilczynski@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>

Lorenzo Pieralisi (5):
  of/irq: Add msi-parent check to of_msi_xlate()
  of/irq: Fix OF node refcount in of_msi_get_domain()
  of/irq: Export of_msi_xlate() for module usage
  PCI: iproc: Implement MSI controller node detection with
    of_msi_xlate()
  irqchip/gic-its: Rework platform MSI deviceID detection

 drivers/irqchip/irq-gic-its-msi-parent.c | 91 ++++++------------------
 drivers/of/irq.c                         | 43 +++++++++--
 drivers/pci/controller/pcie-iproc.c      | 22 ++----
 3 files changed, 67 insertions(+), 89 deletions(-)

-- 
2.50.1

[PATCH v3 1/5] of/irq: Add msi-parent check to of_msi_xlate()

[Lorenzo Pieralisi]

In some legacy platforms the MSI controller for a PCI host bridge is
identified by an msi-parent property whose phandle points at an MSI
controller node with no #msi-cells property, that implicitly
means #msi-cells == 0.

For such platforms, mapping a device ID and retrieving the MSI controller
node becomes simply a matter of checking whether in the device hierarchy
there is an msi-parent property pointing at an MSI controller node with
such characteristics.

Add a helper function to of_msi_xlate() to check the msi-parent property in
addition to msi-map and retrieve the MSI controller node (with a 1:1 ID
deviceID-IN<->deviceID-OUT  mapping) to provide support for deviceID
mapping and MSI controller node retrieval for such platforms.

Fixes: 57d72196dfc8 ("irqchip/gic-v5: Add GICv5 ITS support")
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Sascha Bischoff <sascha.bischoff@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
---
 drivers/of/irq.c | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 65c3c23255b7..e67b2041e73b 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -671,6 +671,35 @@ void __init of_irq_init(const struct of_device_id *matches)
 	}
 }
 
+static int of_check_msi_parent(struct device_node *dev_node, struct device_node **msi_node)
+{
+	struct of_phandle_args msi_spec;
+	int ret;
+
+	/*
+	 * An msi-parent phandle with a missing or == 0 #msi-cells
+	 * property identifies a 1:1 ID translation mapping.
+	 *
+	 * Set the msi controller node if the firmware matches this
+	 * condition.
+	 */
+	ret = of_parse_phandle_with_optional_args(dev_node, "msi-parent", "#msi-cells",
+						  0, &msi_spec);
+	if (!ret) {
+		if ((*msi_node && *msi_node != msi_spec.np) || msi_spec.args_count != 0)
+			ret = -EINVAL;
+
+		if (!ret) {
+			/* Return with a node reference held */
+			*msi_node = msi_spec.np;
+			return 0;
+		}
+		of_node_put(msi_spec.np);
+	}
+
+	return ret;
+}
+
 /**
  * of_msi_xlate - map a MSI ID and find relevant MSI controller node
  * @dev: device for which the mapping is to be done.
@@ -678,7 +707,7 @@ void __init of_irq_init(const struct of_device_id *matches)
  * @id_in: Device ID.
  *
  * Walk up the device hierarchy looking for devices with a "msi-map"
- * property. If found, apply the mapping to @id_in.
+ * or "msi-parent" property. If found, apply the mapping to @id_in.
  * If @msi_np points to a non-NULL device node pointer, only entries targeting
  * that node will be matched; if it points to a NULL value, it will receive the
  * device node of the first matching target phandle, with a reference held.
@@ -692,12 +721,15 @@ u32 of_msi_xlate(struct device *dev, struct device_node **msi_np, u32 id_in)
 
 	/*
 	 * Walk up the device parent links looking for one with a
-	 * "msi-map" property.
+	 * "msi-map" or an "msi-parent" property.
 	 */
-	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent)
+	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent) {
 		if (!of_map_id(parent_dev->of_node, id_in, "msi-map",
 				"msi-map-mask", msi_np, &id_out))
 			break;
+		if (!of_check_msi_parent(parent_dev->of_node, msi_np))
+			break;
+	}
 	return id_out;
 }
 
-- 
2.50.1

[PATCH v3 2/5] of/irq: Fix OF node refcount in of_msi_get_domain()

[Lorenzo Pieralisi]

In of_msi_get_domain() if the iterator loop stops early because an
irq_domain match is detected, an of_node_put() on the iterator node is
needed to keep the OF node refcount in sync.

Add it.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Cc: Rob Herring <robh@kernel.org>
---
 drivers/of/irq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index e67b2041e73b..9f6cd5abba76 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -773,8 +773,10 @@ struct irq_domain *of_msi_get_domain(struct device *dev,
 
 	of_for_each_phandle(&it, err, np, "msi-parent", "#msi-cells", 0) {
 		d = irq_find_matching_host(it.node, token);
-		if (d)
+		if (d) {
+			of_node_put(it.node);
 			return d;
+		}
 	}
 
 	return NULL;
-- 
2.50.1

[PATCH v3 3/5] of/irq: Export of_msi_xlate() for module usage

[Lorenzo Pieralisi]

of_msi_xlate() is required by drivers that can be configured
as modular, export the symbol.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Rob Herring <robh@kernel.org>
---
 drivers/of/irq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 9f6cd5abba76..889d0dfbcb3f 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -732,6 +732,7 @@ u32 of_msi_xlate(struct device *dev, struct device_node **msi_np, u32 id_in)
 	}
 	return id_out;
 }
+EXPORT_SYMBOL_GPL(of_msi_xlate);
 
 /**
  * of_msi_map_get_device_domain - Use msi-map to find the relevant MSI domain
-- 
2.50.1

[PATCH v3 4/5] PCI: iproc: Implement MSI controller node detection with of_msi_xlate()

[Lorenzo Pieralisi]

The functionality implemented in the iproc driver in order to detect an
OF MSI controller node is now fully implemented in of_msi_xlate().

Replace the current msi-map/msi-parent parsing code with of_msi_xlate().

Since of_msi_xlate() is also a deviceID mapping API, pass in a fictitious
0 as deviceID - the driver only requires detecting the OF MSI controller
node not the deviceID mapping per-se (of_msi_xlate() return value is
ignored for the same reason).

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: "Krzysztof Wilczyński" <kwilczynski@kernel.org>
---
 drivers/pci/controller/pcie-iproc.c | 22 +++++-----------------
 1 file changed, 5 insertions(+), 17 deletions(-)

diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
index 22134e95574b..ccf71993ea35 100644
--- a/drivers/pci/controller/pcie-iproc.c
+++ b/drivers/pci/controller/pcie-iproc.c
@@ -17,6 +17,7 @@
 #include <linux/irqchip/arm-gic-v3.h>
 #include <linux/platform_device.h>
 #include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/phy/phy.h>
@@ -1337,29 +1338,16 @@ static int iproc_pcie_msi_steer(struct iproc_pcie *pcie,
 
 static int iproc_pcie_msi_enable(struct iproc_pcie *pcie)
 {
-	struct device_node *msi_node;
+	struct device_node *msi_node = NULL;
 	int ret;
 
 	/*
 	 * Either the "msi-parent" or the "msi-map" phandle needs to exist
 	 * for us to obtain the MSI node.
 	 */
-
-	msi_node = of_parse_phandle(pcie->dev->of_node, "msi-parent", 0);
-	if (!msi_node) {
-		const __be32 *msi_map = NULL;
-		int len;
-		u32 phandle;
-
-		msi_map = of_get_property(pcie->dev->of_node, "msi-map", &len);
-		if (!msi_map)
-			return -ENODEV;
-
-		phandle = be32_to_cpup(msi_map + 1);
-		msi_node = of_find_node_by_phandle(phandle);
-		if (!msi_node)
-			return -ENODEV;
-	}
+	of_msi_xlate(pcie->dev, &msi_node, 0);
+	if (!msi_node)
+		return -ENODEV;
 
 	/*
 	 * Certain revisions of the iProc PCIe controller require additional
-- 
2.50.1

[PATCH v3 5/5] irqchip/gic-its: Rework platform MSI deviceID detection

[Lorenzo Pieralisi]

Current code retrieving platform devices MSI devID in the GIC ITS MSI
parent helpers suffers from some minor issues:

- It leaks a struct device_node reference
- It is duplicated between GICv3 and GICv5 for no good reason
- It does not use the OF phandle iterator code that simplifies
  the msi-parent property parsing

Consolidate GIC v3 and v5 deviceID retrieval in a function that addresses
the full set of issues in one go by merging GIC v3 and v5 code and
converting the msi-parent parsing loop to the more modern OF phandle
iterator API, fixing the struct device_node reference leak in the process.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Sascha Bischoff <sascha.bischoff@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Frank Li <Frank.Li@nxp.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 drivers/irqchip/irq-gic-its-msi-parent.c | 91 ++++++------------------
 1 file changed, 23 insertions(+), 68 deletions(-)

diff --git a/drivers/irqchip/irq-gic-its-msi-parent.c b/drivers/irqchip/irq-gic-its-msi-parent.c
index eb1473f1448a..12f45228c867 100644
--- a/drivers/irqchip/irq-gic-its-msi-parent.c
+++ b/drivers/irqchip/irq-gic-its-msi-parent.c
@@ -142,83 +142,38 @@ static int its_v5_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
 #define its_v5_pci_msi_prepare	NULL
 #endif /* !CONFIG_PCI_MSI */
 
-static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
-				  u32 *dev_id)
+static int of_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev, u32 *dev_id,
+				phys_addr_t *pa)
 {
-	int ret, index = 0;
+	struct of_phandle_iterator it;
+	int ret;
 
 	/* Suck the DeviceID out of the msi-parent property */
-	do {
-		struct of_phandle_args args;
+	of_for_each_phandle(&it, ret, dev->of_node, "msi-parent", "#msi-cells", -1) {
+		/* GICv5 ITS domain matches the MSI controller node parent */
+		struct device_node *np __free(device_node) = pa ? of_get_parent(it.node)
+								: of_node_get(it.node);
 
-		ret = of_parse_phandle_with_args(dev->of_node,
-						 "msi-parent", "#msi-cells",
-						 index, &args);
-		if (args.np == irq_domain_get_of_node(domain)) {
-			if (WARN_ON(args.args_count != 1))
-				return -EINVAL;
-			*dev_id = args.args[0];
-			break;
-		}
-		index++;
-	} while (!ret);
+		if (np == irq_domain_get_of_node(domain)) {
+			u32 args;
 
-	if (ret) {
-		struct device_node *np = NULL;
+			if (WARN_ON(of_phandle_iterator_args(&it, &args, 1) != 1))
+				ret = -EINVAL;
 
-		ret = of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &np, dev_id);
-		if (np)
-			of_node_put(np);
-	}
+			if (!ret && pa)
+				ret = its_translate_frame_address(it.node, pa);
 
-	return ret;
-}
+			if (!ret)
+				*dev_id = args;
 
-static int of_v5_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev,
-				   u32 *dev_id, phys_addr_t *pa)
-{
-	int ret, index = 0;
-	/*
-	 * Retrieve the DeviceID and the ITS translate frame node pointer
-	 * out of the msi-parent property.
-	 */
-	do {
-		struct of_phandle_args args;
-
-		ret = of_parse_phandle_with_args(dev->of_node,
-						 "msi-parent", "#msi-cells",
-						 index, &args);
-		if (ret)
-			break;
-		/*
-		 * The IRQ domain fwnode is the msi controller parent
-		 * in GICv5 (where the msi controller nodes are the
-		 * ITS translate frames).
-		 */
-		if (args.np->parent == irq_domain_get_of_node(domain)) {
-			if (WARN_ON(args.args_count != 1))
-				return -EINVAL;
-			*dev_id = args.args[0];
-
-			ret = its_translate_frame_address(args.np, pa);
-			if (ret)
-				return -ENODEV;
-			break;
-		}
-		index++;
-	} while (!ret);
-
-	if (ret) {
-		struct device_node *np = NULL;
-
-		ret = of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &np, dev_id);
-		if (np) {
-			ret = its_translate_frame_address(np, pa);
-			of_node_put(np);
+			of_node_put(it.node);
+			return ret;
 		}
 	}
 
-	return ret;
+	struct device_node *msi_ctrl __free(device_node) = NULL;
+
+	return of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &msi_ctrl, dev_id);
 }
 
 int __weak iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
@@ -234,7 +189,7 @@ static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
 	int ret;
 
 	if (dev->of_node)
-		ret = of_pmsi_get_dev_id(domain->parent, dev, &dev_id);
+		ret = of_pmsi_get_msi_info(domain->parent, dev, &dev_id, NULL);
 	else
 		ret = iort_pmsi_get_dev_id(dev, &dev_id);
 	if (ret)
@@ -262,7 +217,7 @@ static int its_v5_pmsi_prepare(struct irq_domain *domain, struct device *dev,
 	if (!dev->of_node)
 		return -ENODEV;
 
-	ret = of_v5_pmsi_get_msi_info(domain->parent, dev, &dev_id, &pa);
+	ret = of_pmsi_get_msi_info(domain->parent, dev, &dev_id, &pa);
 	if (ret)
 		return ret;
 
-- 
2.50.1

Re: [PATCH v3 0/5] of/irq: Misc msi-parent handling fixes/clean-ups

[Frank Li]

On Fri, Oct 17, 2025 at 10:47:47AM +0200, Lorenzo Pieralisi wrote:
> This is series is a follow up to [1] - with additional patches that are
> addressing Rob's feedback (pcie-layerscape-gen4 was removed from the
> kernel, Yay !) and other bits and bobs I noticed while staring at the code.
>
> Patch (1) is a fix and technically we would like to get it in v6.18 please.
>
> Patch (4) is compile-tested only, I can not run it on HW, I do not have it,
> Scott, Ray please test it if you can.
>
> v2 -> v3:
> 	- Added additional patch to export of_msi_xlate()
> 	- Merged Marc's ITS parent diff
> 	- Added trailers, fixed commit logs
>
> v2: https://lore.kernel.org/lkml/20251014095845.1310624-1-lpieralisi@kernel.org/
> v1: https://lore.kernel.org/lkml/20250916091858.257868-1-lpieralisi@kernel.org/
>
> [1] https://lore.kernel.org/lkml/20250916091858.257868-1-lpieralisi@kernel.org/
>
> Cc: Sascha Bischoff <sascha.bischoff@arm.com>
> Cc: Scott Branden <sbranden@broadcom.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Ray Jui <rjui@broadcom.com>
> Cc: Frank Li <Frank.Li@nxp.com>
> Cc: Manivannan Sadhasivam <mani@kernel.org>
> Cc: "Krzysztof Wilczyński" <kwilczynski@kernel.org>
> Cc: Marc Zyngier <maz@kernel.org>

I tested epf msi doorbell, no regression. My test cover only using msi-map
code path.

For whole series

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>
> Lorenzo Pieralisi (5):
>   of/irq: Add msi-parent check to of_msi_xlate()
>   of/irq: Fix OF node refcount in of_msi_get_domain()
>   of/irq: Export of_msi_xlate() for module usage
>   PCI: iproc: Implement MSI controller node detection with
>     of_msi_xlate()
>   irqchip/gic-its: Rework platform MSI deviceID detection
>
>  drivers/irqchip/irq-gic-its-msi-parent.c | 91 ++++++------------------
>  drivers/of/irq.c                         | 43 +++++++++--
>  drivers/pci/controller/pcie-iproc.c      | 22 ++----
>  3 files changed, 67 insertions(+), 89 deletions(-)
>
> --
> 2.50.1
>

Re: [PATCH v3 1/5] of/irq: Add msi-parent check to of_msi_xlate()

[Rob Herring]

On Fri, Oct 17, 2025 at 10:47:48AM +0200, Lorenzo Pieralisi wrote:
> In some legacy platforms the MSI controller for a PCI host bridge is
> identified by an msi-parent property whose phandle points at an MSI
> controller node with no #msi-cells property, that implicitly
> means #msi-cells == 0.
> 
> For such platforms, mapping a device ID and retrieving the MSI controller
> node becomes simply a matter of checking whether in the device hierarchy
> there is an msi-parent property pointing at an MSI controller node with
> such characteristics.
> 
> Add a helper function to of_msi_xlate() to check the msi-parent property in
> addition to msi-map and retrieve the MSI controller node (with a 1:1 ID
> deviceID-IN<->deviceID-OUT  mapping) to provide support for deviceID
> mapping and MSI controller node retrieval for such platforms.
> 
> Fixes: 57d72196dfc8 ("irqchip/gic-v5: Add GICv5 ITS support")
> Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
> Cc: Sascha Bischoff <sascha.bischoff@arm.com>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Marc Zyngier <maz@kernel.org>
> ---
>  drivers/of/irq.c | 38 +++++++++++++++++++++++++++++++++++---
>  1 file changed, 35 insertions(+), 3 deletions(-)

It all looks good to me other than 1 nit below. How do you propose 
merging the series? I can take the first 3 for 6.18 and then patches 4 
and 5 can go via their respective trees for 6.19?

> 
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index 65c3c23255b7..e67b2041e73b 100644
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -671,6 +671,35 @@ void __init of_irq_init(const struct of_device_id *matches)
>  	}
>  }
>  
> +static int of_check_msi_parent(struct device_node *dev_node, struct device_node **msi_node)
> +{
> +	struct of_phandle_args msi_spec;
> +	int ret;
> +
> +	/*
> +	 * An msi-parent phandle with a missing or == 0 #msi-cells
> +	 * property identifies a 1:1 ID translation mapping.
> +	 *
> +	 * Set the msi controller node if the firmware matches this
> +	 * condition.
> +	 */
> +	ret = of_parse_phandle_with_optional_args(dev_node, "msi-parent", "#msi-cells",
> +						  0, &msi_spec);
> +	if (!ret) {

if (ret)
	return ret;

And then save a level of indentation.

> +		if ((*msi_node && *msi_node != msi_spec.np) || msi_spec.args_count != 0)
> +			ret = -EINVAL;
> +
> +		if (!ret) {
> +			/* Return with a node reference held */
> +			*msi_node = msi_spec.np;
> +			return 0;
> +		}
> +		of_node_put(msi_spec.np);
> +	}
> +
> +	return ret;
> +}
> +
>  /**
>   * of_msi_xlate - map a MSI ID and find relevant MSI controller node
>   * @dev: device for which the mapping is to be done.
> @@ -678,7 +707,7 @@ void __init of_irq_init(const struct of_device_id *matches)
>   * @id_in: Device ID.
>   *
>   * Walk up the device hierarchy looking for devices with a "msi-map"
> - * property. If found, apply the mapping to @id_in.
> + * or "msi-parent" property. If found, apply the mapping to @id_in.
>   * If @msi_np points to a non-NULL device node pointer, only entries targeting
>   * that node will be matched; if it points to a NULL value, it will receive the
>   * device node of the first matching target phandle, with a reference held.
> @@ -692,12 +721,15 @@ u32 of_msi_xlate(struct device *dev, struct device_node **msi_np, u32 id_in)
>  
>  	/*
>  	 * Walk up the device parent links looking for one with a
> -	 * "msi-map" property.
> +	 * "msi-map" or an "msi-parent" property.
>  	 */
> -	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent)
> +	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent) {
>  		if (!of_map_id(parent_dev->of_node, id_in, "msi-map",
>  				"msi-map-mask", msi_np, &id_out))
>  			break;
> +		if (!of_check_msi_parent(parent_dev->of_node, msi_np))
> +			break;
> +	}
>  	return id_out;
>  }
>  
> -- 
> 2.50.1
> 

Re: [PATCH v3 1/5] of/irq: Add msi-parent check to of_msi_xlate()

[Lorenzo Pieralisi]

On Tue, Oct 21, 2025 at 06:55:17AM -0500, Rob Herring wrote:
> On Fri, Oct 17, 2025 at 10:47:48AM +0200, Lorenzo Pieralisi wrote:
> > In some legacy platforms the MSI controller for a PCI host bridge is
> > identified by an msi-parent property whose phandle points at an MSI
> > controller node with no #msi-cells property, that implicitly
> > means #msi-cells == 0.
> > 
> > For such platforms, mapping a device ID and retrieving the MSI controller
> > node becomes simply a matter of checking whether in the device hierarchy
> > there is an msi-parent property pointing at an MSI controller node with
> > such characteristics.
> > 
> > Add a helper function to of_msi_xlate() to check the msi-parent property in
> > addition to msi-map and retrieve the MSI controller node (with a 1:1 ID
> > deviceID-IN<->deviceID-OUT  mapping) to provide support for deviceID
> > mapping and MSI controller node retrieval for such platforms.
> > 
> > Fixes: 57d72196dfc8 ("irqchip/gic-v5: Add GICv5 ITS support")
> > Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
> > Cc: Sascha Bischoff <sascha.bischoff@arm.com>
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Marc Zyngier <maz@kernel.org>
> > ---
> >  drivers/of/irq.c | 38 +++++++++++++++++++++++++++++++++++---
> >  1 file changed, 35 insertions(+), 3 deletions(-)
> 
> It all looks good to me other than 1 nit below. How do you propose 
> merging the series? I can take the first 3 for 6.18 and then patches 4 
> and 5 can go via their respective trees for 6.19?

Yep, though patch (3) isn't really a fix so not sure it is v6.18 material
but that's up to you.

I'd leave patch (1) brewing in -next if possible a little bit - it should
not cause any issues but it might.

> > 
> > diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> > index 65c3c23255b7..e67b2041e73b 100644
> > --- a/drivers/of/irq.c
> > +++ b/drivers/of/irq.c
> > @@ -671,6 +671,35 @@ void __init of_irq_init(const struct of_device_id *matches)
> >  	}
> >  }
> >  
> > +static int of_check_msi_parent(struct device_node *dev_node, struct device_node **msi_node)
> > +{
> > +	struct of_phandle_args msi_spec;
> > +	int ret;
> > +
> > +	/*
> > +	 * An msi-parent phandle with a missing or == 0 #msi-cells
> > +	 * property identifies a 1:1 ID translation mapping.
> > +	 *
> > +	 * Set the msi controller node if the firmware matches this
> > +	 * condition.
> > +	 */
> > +	ret = of_parse_phandle_with_optional_args(dev_node, "msi-parent", "#msi-cells",
> > +						  0, &msi_spec);
> > +	if (!ret) {
> 
> if (ret)
> 	return ret;
> 
> And then save a level of indentation.

Fixed - sent v4.

Thanks !
Lorenzo

> > +		if ((*msi_node && *msi_node != msi_spec.np) || msi_spec.args_count != 0)
> > +			ret = -EINVAL;
> > +
> > +		if (!ret) {
> > +			/* Return with a node reference held */
> > +			*msi_node = msi_spec.np;
> > +			return 0;
> > +		}
> > +		of_node_put(msi_spec.np);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> >  /**
> >   * of_msi_xlate - map a MSI ID and find relevant MSI controller node
> >   * @dev: device for which the mapping is to be done.
> > @@ -678,7 +707,7 @@ void __init of_irq_init(const struct of_device_id *matches)
> >   * @id_in: Device ID.
> >   *
> >   * Walk up the device hierarchy looking for devices with a "msi-map"
> > - * property. If found, apply the mapping to @id_in.
> > + * or "msi-parent" property. If found, apply the mapping to @id_in.
> >   * If @msi_np points to a non-NULL device node pointer, only entries targeting
> >   * that node will be matched; if it points to a NULL value, it will receive the
> >   * device node of the first matching target phandle, with a reference held.
> > @@ -692,12 +721,15 @@ u32 of_msi_xlate(struct device *dev, struct device_node **msi_np, u32 id_in)
> >  
> >  	/*
> >  	 * Walk up the device parent links looking for one with a
> > -	 * "msi-map" property.
> > +	 * "msi-map" or an "msi-parent" property.
> >  	 */
> > -	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent)
> > +	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent) {
> >  		if (!of_map_id(parent_dev->of_node, id_in, "msi-map",
> >  				"msi-map-mask", msi_np, &id_out))
> >  			break;
> > +		if (!of_check_msi_parent(parent_dev->of_node, msi_np))
> > +			break;
> > +	}
> >  	return id_out;
> >  }
> >  
> > -- 
> > 2.50.1
> >