[PATCH v3 0/2] Add support for AMD Versal Gen 2 MDB PCIe RP PERST#

[PATCH v3 0/2] Add support for AMD Versal Gen 2 MDB PCIe RP PERST#

[Sai Krishna Musham]

Add reset-gpios property to PCI bridge node

Add support for PCIe Root Port PERST# signal handling

Sai Krishna Musham (2):
  dt-bindings: PCI: amd-mdb: Add reset-gpios property for PCIe RP PERST#
    handling
  PCI: amd-mdb: Add support for PCIe RP PERST# signal handling

 .../bindings/pci/amd,versal2-mdb-host.yaml    | 26 +++++++++++
 drivers/pci/controller/dwc/pcie-amd-mdb.c     | 45 ++++++++++++++++++-
 2 files changed, 70 insertions(+), 1 deletion(-)

-- 
2.43.0

[PATCH v3 1/2] dt-bindings: PCI: amd-mdb: Add reset-gpios property for PCIe RP PERST# handling

[Sai Krishna Musham]

Add support for the `reset-gpios` property in the PCIe Root Port (RP)
child node to handle the PERST# signal via GPIO. Update the example
to reflect this addition.

Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
---
Changes in v3:
- Move reset-gpios to PCI bridge node.

Changes in v2:
- Update commit message
---
 .../bindings/pci/amd,versal2-mdb-host.yaml    | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
index 43dc2585c237..3ffe4512650d 100644
--- a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
+++ b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
@@ -71,6 +71,21 @@ properties:
       - "#address-cells"
       - "#interrupt-cells"
 
+patternProperties:
+  '^pcie@[0-2],0$':
+    type: object
+    $ref: /schemas/pci/pci-pci-bridge.yaml#
+
+    properties:
+      reg:
+        maxItems: 1
+
+      reset-gpios:
+        description: GPIO controlled connection to PERST# signal
+        maxItems: 1
+
+    unevaluatedProperties: false
+
 required:
   - reg
   - reg-names
@@ -87,6 +102,7 @@ examples:
   - |
     #include <dt-bindings/interrupt-controller/arm-gic.h>
     #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/gpio/gpio.h>
 
     soc {
         #address-cells = <2>;
@@ -112,6 +128,16 @@ examples:
             #size-cells = <2>;
             #interrupt-cells = <1>;
             device_type = "pci";
+
+            pcie@0,0 {
+                device_type = "pci";
+                reg = <0x0 0x0 0x0 0x0 0x0>;
+                reset-gpios = <&tca6416_u37 7 GPIO_ACTIVE_LOW>;
+                #address-cells = <3>;
+                #size-cells = <2>;
+                ranges;
+            };
+
             pcie_intc_0: interrupt-controller {
                 #address-cells = <0>;
                 #interrupt-cells = <1>;
-- 
2.43.0

Re: [PATCH v3 1/2] dt-bindings: PCI: amd-mdb: Add reset-gpios property for PCIe RP PERST# handling

[Krishna Chaitanya Chundru]

On 6/18/2025 1:39 PM, Sai Krishna Musham wrote:
> Add support for the `reset-gpios` property in the PCIe Root Port (RP)
> child node to handle the PERST# signal via GPIO. Update the example
> to reflect this addition.
> 
> Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
> ---
> Changes in v3:
> - Move reset-gpios to PCI bridge node.
> 
> Changes in v2:
> - Update commit message
> ---
>   .../bindings/pci/amd,versal2-mdb-host.yaml    | 26 +++++++++++++++++++
>   1 file changed, 26 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> index 43dc2585c237..3ffe4512650d 100644
> --- a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> +++ b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> @@ -71,6 +71,21 @@ properties:
>         - "#address-cells"
>         - "#interrupt-cells"
>   
> +patternProperties:
> +  '^pcie@[0-2],0$':
> +    type: object
> +    $ref: /schemas/pci/pci-pci-bridge.yaml#
> +
> +    properties:
> +      reg:
> +        maxItems: 1
> +
> +      reset-gpios:
> +        description: GPIO controlled connection to PERST# signal
> +        maxItems: 1
> +
This is already part of pci-bus-common.yaml in dtschema no need to
define it again here.

- Krishna Chaitanya.

> +    unevaluatedProperties: false
> +
>   required:
>     - reg
>     - reg-names
> @@ -87,6 +102,7 @@ examples:
>     - |
>       #include <dt-bindings/interrupt-controller/arm-gic.h>
>       #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/gpio/gpio.h>
>   
>       soc {
>           #address-cells = <2>;
> @@ -112,6 +128,16 @@ examples:
>               #size-cells = <2>;
>               #interrupt-cells = <1>;
>               device_type = "pci";
> +
> +            pcie@0,0 {
> +                device_type = "pci";
> +                reg = <0x0 0x0 0x0 0x0 0x0>;
> +                reset-gpios = <&tca6416_u37 7 GPIO_ACTIVE_LOW>;
> +                #address-cells = <3>;
> +                #size-cells = <2>;
> +                ranges;
> +            };
> +
>               pcie_intc_0: interrupt-controller {
>                   #address-cells = <0>;
>                   #interrupt-cells = <1>;

RE: [PATCH v3 1/2] dt-bindings: PCI: amd-mdb: Add reset-gpios property for PCIe RP PERST# handling

[Musham, Sai Krishna]

[AMD Official Use Only - AMD Internal Distribution Only]

Hi Krishna Chaitanya,

> -----Original Message-----
> From: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
> Sent: Monday, June 23, 2025 1:22 PM
> To: Musham, Sai Krishna <sai.krishna.musham@amd.com>;
> bhelgaas@google.com; lpieralisi@kernel.org; kw@linux.com; mani@kernel.org;
> robh@kernel.org; krzk+dt@kernel.org; conor+dt@kernel.org; cassel@kernel.org
> Cc: linux-pci@vger.kernel.org; devicetree@vger.kernel.org; linux-
> kernel@vger.kernel.org; Simek, Michal <michal.simek@amd.com>; Gogada, Bharat
> Kumar <bharat.kumar.gogada@amd.com>; Havalige, Thippeswamy
> <thippeswamy.havalige@amd.com>
> Subject: Re: [PATCH v3 1/2] dt-bindings: PCI: amd-mdb: Add reset-gpios property
> for PCIe RP PERST# handling
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On 6/18/2025 1:39 PM, Sai Krishna Musham wrote:
> > Add support for the `reset-gpios` property in the PCIe Root Port (RP)
> > child node to handle the PERST# signal via GPIO. Update the example
> > to reflect this addition.
> >
> > Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
> > ---
> > Changes in v3:
> > - Move reset-gpios to PCI bridge node.
> >
> > Changes in v2:
> > - Update commit message
> > ---
> >   .../bindings/pci/amd,versal2-mdb-host.yaml    | 26 +++++++++++++++++++
> >   1 file changed, 26 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> > index 43dc2585c237..3ffe4512650d 100644
> > --- a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> > +++ b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> > @@ -71,6 +71,21 @@ properties:
> >         - "#address-cells"
> >         - "#interrupt-cells"
> >
> > +patternProperties:
> > +  '^pcie@[0-2],0$':
> > +    type: object
> > +    $ref: /schemas/pci/pci-pci-bridge.yaml#
> > +
> > +    properties:
> > +      reg:
> > +        maxItems: 1
> > +
> > +      reset-gpios:
> > +        description: GPIO controlled connection to PERST# signal
> > +        maxItems: 1
> > +
> This is already part of pci-bus-common.yaml in dtschema no need to
> define it again here.
>

Thanks for the review. Sure, I will remove it.

> - Krishna Chaitanya.
>
> > +    unevaluatedProperties: false
> > +
> >   required:
> >     - reg
> >     - reg-names
> > @@ -87,6 +102,7 @@ examples:
> >     - |
> >       #include <dt-bindings/interrupt-controller/arm-gic.h>
> >       #include <dt-bindings/interrupt-controller/irq.h>
> > +    #include <dt-bindings/gpio/gpio.h>
> >
> >       soc {
> >           #address-cells = <2>;
> > @@ -112,6 +128,16 @@ examples:
> >               #size-cells = <2>;
> >               #interrupt-cells = <1>;
> >               device_type = "pci";
> > +
> > +            pcie@0,0 {
> > +                device_type = "pci";
> > +                reg = <0x0 0x0 0x0 0x0 0x0>;
> > +                reset-gpios = <&tca6416_u37 7 GPIO_ACTIVE_LOW>;
> > +                #address-cells = <3>;
> > +                #size-cells = <2>;
> > +                ranges;
> > +            };
> > +
> >               pcie_intc_0: interrupt-controller {
> >                   #address-cells = <0>;
> >                   #interrupt-cells = <1>;

[PATCH v3 2/2] PCI: amd-mdb: Add support for PCIe RP PERST# signal handling

[Sai Krishna Musham]

Add GPIO based PERST# signal handling for AMD Versal Gen 2 MDB
PCIe Root Port.

Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
---
Changes in v3:
- Implement amd_mdb_parse_pcie_port to parse bridge node for reset-gpios property.

Changes in v2:
- Change delay to PCIE_T_PVPERL_MS
---
 drivers/pci/controller/dwc/pcie-amd-mdb.c | 45 ++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c b/drivers/pci/controller/dwc/pcie-amd-mdb.c
index 4eb2a4e8189d..b4c5b71900a5 100644
--- a/drivers/pci/controller/dwc/pcie-amd-mdb.c
+++ b/drivers/pci/controller/dwc/pcie-amd-mdb.c
@@ -18,6 +18,7 @@
 #include <linux/resource.h>
 #include <linux/types.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 #define AMD_MDB_TLP_IR_STATUS_MISC		0x4C0
@@ -63,6 +64,7 @@ struct amd_mdb_pcie {
 	void __iomem			*slcr;
 	struct irq_domain		*intx_domain;
 	struct irq_domain		*mdb_domain;
+	struct gpio_desc		*perst_gpio;
 	int				intx_irq;
 };
 
@@ -284,7 +286,7 @@ static int amd_mdb_pcie_init_irq_domains(struct amd_mdb_pcie *pcie,
 	struct device_node *pcie_intc_node;
 	int err;
 
-	pcie_intc_node = of_get_next_child(node, NULL);
+	pcie_intc_node = of_get_child_by_name(node, "interrupt-controller");
 	if (!pcie_intc_node) {
 		dev_err(dev, "No PCIe Intc node found\n");
 		return -ENODEV;
@@ -402,6 +404,34 @@ static int amd_mdb_setup_irq(struct amd_mdb_pcie *pcie,
 	return 0;
 }
 
+static int amd_mdb_parse_pcie_port(struct amd_mdb_pcie *pcie)
+{
+	struct device *dev = pcie->pci.dev;
+	struct device_node *pcie_port_node;
+
+	pcie_port_node = of_get_next_child_with_prefix(dev->of_node, NULL, "pcie");
+	if (!pcie_port_node) {
+		dev_err(dev, "No PCIe Bridge node found\n");
+		return -ENODEV;
+	}
+
+	/* Request the GPIO for PCIe reset signal and assert */
+	pcie->perst_gpio = devm_fwnode_gpiod_get(dev, of_fwnode_handle(pcie_port_node),
+						 "reset", GPIOD_OUT_HIGH, NULL);
+	if (IS_ERR(pcie->perst_gpio)) {
+		if (PTR_ERR(pcie->perst_gpio) != -ENOENT) {
+			of_node_put(pcie_port_node);
+			return dev_err_probe(dev, PTR_ERR(pcie->perst_gpio),
+					     "Failed to request reset GPIO\n");
+		}
+		pcie->perst_gpio = NULL;
+	}
+
+	of_node_put(pcie_port_node);
+
+	return 0;
+}
+
 static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
 				 struct platform_device *pdev)
 {
@@ -426,6 +456,14 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
 
 	pp->ops = &amd_mdb_pcie_host_ops;
 
+	if (pcie->perst_gpio) {
+		mdelay(PCIE_T_PVPERL_MS);
+
+		/* Deassert the reset signal */
+		gpiod_set_value_cansleep(pcie->perst_gpio, 0);
+		mdelay(PCIE_T_RRS_READY_MS);
+	}
+
 	err = dw_pcie_host_init(pp);
 	if (err) {
 		dev_err(dev, "Failed to initialize host, err=%d\n", err);
@@ -444,6 +482,7 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct amd_mdb_pcie *pcie;
 	struct dw_pcie *pci;
+	int ret;
 
 	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
 	if (!pcie)
@@ -454,6 +493,10 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcie);
 
+	ret = amd_mdb_parse_pcie_port(pcie);
+	if (ret)
+		return ret;
+
 	return amd_mdb_add_pcie_port(pcie, pdev);
 }
 
-- 
2.43.0

Re: [PATCH v3 2/2] PCI: amd-mdb: Add support for PCIe RP PERST# signal handling

[kernel test robot]

Hi Sai,

kernel test robot noticed the following build warnings:

[auto build test WARNING on pci/next]
[also build test WARNING on pci/for-linus linus/master v6.16-rc3 next-20250623]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sai-Krishna-Musham/dt-bindings-PCI-amd-mdb-Add-reset-gpios-property-for-PCIe-RP-PERST-handling/20250618-161100
base:   https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git next
patch link:    https://lore.kernel.org/r/20250618080931.2472366-3-sai.krishna.musham%40amd.com
patch subject: [PATCH v3 2/2] PCI: amd-mdb: Add support for PCIe RP PERST# signal handling
config: csky-randconfig-002-20250621 (https://download.01.org/0day-ci/archive/20250624/202506241020.rPD1a2Vr-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250624/202506241020.rPD1a2Vr-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506241020.rPD1a2Vr-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> Warning: drivers/pci/controller/dwc/pcie-amd-mdb.c:68 struct member 'perst_gpio' not described in 'amd_mdb_pcie'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v3 2/2] PCI: amd-mdb: Add support for PCIe RP PERST# signal handling

[Bjorn Helgaas]

On Wed, Jun 18, 2025 at 01:39:31PM +0530, Sai Krishna Musham wrote:
> Add GPIO based PERST# signal handling for AMD Versal Gen 2 MDB
> PCIe Root Port.
> 
> Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
> ---
> Changes in v3:
> - Implement amd_mdb_parse_pcie_port to parse bridge node for reset-gpios property.
> 
> Changes in v2:
> - Change delay to PCIE_T_PVPERL_MS

v3 https://lore.kernel.org/r/20250618080931.2472366-1-sai.krishna.musham@amd.com/
v2 https://lore.kernel.org/r/20250429090046.1512000-1-sai.krishna.musham@amd.com/
v1 https://lore.kernel.org/r/20250326041507.98232-1-sai.krishna.musham@amd.com/

> ---
>  drivers/pci/controller/dwc/pcie-amd-mdb.c | 45 ++++++++++++++++++++++-
>  1 file changed, 44 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> index 4eb2a4e8189d..b4c5b71900a5 100644
> --- a/drivers/pci/controller/dwc/pcie-amd-mdb.c
> +++ b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> @@ -18,6 +18,7 @@
>  #include <linux/resource.h>
>  #include <linux/types.h>
>  
> +#include "../../pci.h"
>  #include "pcie-designware.h"
>  
>  #define AMD_MDB_TLP_IR_STATUS_MISC		0x4C0
> @@ -63,6 +64,7 @@ struct amd_mdb_pcie {
>  	void __iomem			*slcr;
>  	struct irq_domain		*intx_domain;
>  	struct irq_domain		*mdb_domain;
> +	struct gpio_desc		*perst_gpio;
>  	int				intx_irq;
>  };
>  
> @@ -284,7 +286,7 @@ static int amd_mdb_pcie_init_irq_domains(struct amd_mdb_pcie *pcie,
>  	struct device_node *pcie_intc_node;
>  	int err;
>  
> -	pcie_intc_node = of_get_next_child(node, NULL);
> +	pcie_intc_node = of_get_child_by_name(node, "interrupt-controller");

Is this change logically part of the PERST# support?  If not, this
could be a separate patch.

>  	if (!pcie_intc_node) {
>  		dev_err(dev, "No PCIe Intc node found\n");
>  		return -ENODEV;
> @@ -402,6 +404,34 @@ static int amd_mdb_setup_irq(struct amd_mdb_pcie *pcie,
>  	return 0;
>  }
>  
> +static int amd_mdb_parse_pcie_port(struct amd_mdb_pcie *pcie)
> +{
> +	struct device *dev = pcie->pci.dev;
> +	struct device_node *pcie_port_node;
> +
> +	pcie_port_node = of_get_next_child_with_prefix(dev->of_node, NULL, "pcie");
> +	if (!pcie_port_node) {
> +		dev_err(dev, "No PCIe Bridge node found\n");
> +		return -ENODEV;
> +	}
> +
> +	/* Request the GPIO for PCIe reset signal and assert */
> +	pcie->perst_gpio = devm_fwnode_gpiod_get(dev, of_fwnode_handle(pcie_port_node),
> +						 "reset", GPIOD_OUT_HIGH, NULL);
> +	if (IS_ERR(pcie->perst_gpio)) {
> +		if (PTR_ERR(pcie->perst_gpio) != -ENOENT) {
> +			of_node_put(pcie_port_node);
> +			return dev_err_probe(dev, PTR_ERR(pcie->perst_gpio),
> +					     "Failed to request reset GPIO\n");
> +		}
> +		pcie->perst_gpio = NULL;
> +	}
> +
> +	of_node_put(pcie_port_node);
> +
> +	return 0;
> +}
> +
>  static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
>  				 struct platform_device *pdev)
>  {
> @@ -426,6 +456,14 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
>  
>  	pp->ops = &amd_mdb_pcie_host_ops;
>  
> +	if (pcie->perst_gpio) {
> +		mdelay(PCIE_T_PVPERL_MS);
> +
> +		/* Deassert the reset signal */
> +		gpiod_set_value_cansleep(pcie->perst_gpio, 0);
> +		mdelay(PCIE_T_RRS_READY_MS);
> +	}
> +
>  	err = dw_pcie_host_init(pp);
>  	if (err) {
>  		dev_err(dev, "Failed to initialize host, err=%d\n", err);
> @@ -444,6 +482,7 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct amd_mdb_pcie *pcie;
>  	struct dw_pcie *pci;
> +	int ret;
>  
>  	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
>  	if (!pcie)
> @@ -454,6 +493,10 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, pcie);
>  
> +	ret = amd_mdb_parse_pcie_port(pcie);
> +	if (ret)
> +		return ret;
> +
>  	return amd_mdb_add_pcie_port(pcie, pdev);
>  }
>  
> -- 
> 2.43.0
> 

RE: [PATCH v3 2/2] PCI: amd-mdb: Add support for PCIe RP PERST# signal handling

[Musham, Sai Krishna]

[AMD Official Use Only - AMD Internal Distribution Only]

Hi Bjorn,

> -----Original Message-----
> From: Bjorn Helgaas <helgaas@kernel.org>
> Sent: Tuesday, June 24, 2025 9:31 PM
> To: Musham, Sai Krishna <sai.krishna.musham@amd.com>
> Cc: bhelgaas@google.com; lpieralisi@kernel.org; kw@linux.com; mani@kernel.org;
> robh@kernel.org; krzk+dt@kernel.org; conor+dt@kernel.org; cassel@kernel.org;
> linux-pci@vger.kernel.org; devicetree@vger.kernel.org; linux-
> kernel@vger.kernel.org; Simek, Michal <michal.simek@amd.com>; Gogada, Bharat
> Kumar <bharat.kumar.gogada@amd.com>; Havalige, Thippeswamy
> <thippeswamy.havalige@amd.com>
> Subject: Re: [PATCH v3 2/2] PCI: amd-mdb: Add support for PCIe RP PERST#
> signal handling
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Wed, Jun 18, 2025 at 01:39:31PM +0530, Sai Krishna Musham wrote:
> > Add GPIO based PERST# signal handling for AMD Versal Gen 2 MDB
> > PCIe Root Port.
> >
> > Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
> > ---
> > Changes in v3:
> > - Implement amd_mdb_parse_pcie_port to parse bridge node for reset-gpios
> property.
> >
> > Changes in v2:
> > - Change delay to PCIE_T_PVPERL_MS
>
> v3 https://lore.kernel.org/r/20250618080931.2472366-1-
> sai.krishna.musham@amd.com/
> v2 https://lore.kernel.org/r/20250429090046.1512000-1-
> sai.krishna.musham@amd.com/
> v1 https://lore.kernel.org/r/20250326041507.98232-1-
> sai.krishna.musham@amd.com/
>

Sure, I will add the lore links. Thanks

> > ---
> >  drivers/pci/controller/dwc/pcie-amd-mdb.c | 45 ++++++++++++++++++++++-
> >  1 file changed, 44 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c
> b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > index 4eb2a4e8189d..b4c5b71900a5 100644
> > --- a/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > +++ b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > @@ -18,6 +18,7 @@
> >  #include <linux/resource.h>
> >  #include <linux/types.h>
> >
> > +#include "../../pci.h"
> >  #include "pcie-designware.h"
> >
> >  #define AMD_MDB_TLP_IR_STATUS_MISC           0x4C0
> > @@ -63,6 +64,7 @@ struct amd_mdb_pcie {
> >       void __iomem                    *slcr;
> >       struct irq_domain               *intx_domain;
> >       struct irq_domain               *mdb_domain;
> > +     struct gpio_desc                *perst_gpio;
> >       int                             intx_irq;
> >  };
> >
> > @@ -284,7 +286,7 @@ static int amd_mdb_pcie_init_irq_domains(struct
> amd_mdb_pcie *pcie,
> >       struct device_node *pcie_intc_node;
> >       int err;
> >
> > -     pcie_intc_node = of_get_next_child(node, NULL);
> > +     pcie_intc_node = of_get_child_by_name(node, "interrupt-controller");
>
> Is this change logically part of the PERST# support?  If not, this
> could be a separate patch.
>

Yes, this change is logically part of the PERST# support patch.

Previously, the interrupt-controller node was the only child under the PCIe node,
so we used of_get_next_child() to retrieve it. With this patch, a new PCIe bridge
node has been added as a child node, which could lead to ambiguity or incorrect
parsing.

To ensure we explicitly retrieve the correct node and avoid potential issues, I replaced
of_get_next_child() with of_get_child_by_name() to directly access the 'interrupt-controller'
node.

> >       if (!pcie_intc_node) {
> >               dev_err(dev, "No PCIe Intc node found\n");
> >               return -ENODEV;
> > @@ -402,6 +404,34 @@ static int amd_mdb_setup_irq(struct amd_mdb_pcie
> *pcie,
> >       return 0;
> >  }
> >
> > +static int amd_mdb_parse_pcie_port(struct amd_mdb_pcie *pcie)
> > +{
> > +     struct device *dev = pcie->pci.dev;
> > +     struct device_node *pcie_port_node;
> > +
> > +     pcie_port_node = of_get_next_child_with_prefix(dev->of_node, NULL, "pcie");
> > +     if (!pcie_port_node) {
> > +             dev_err(dev, "No PCIe Bridge node found\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     /* Request the GPIO for PCIe reset signal and assert */
> > +     pcie->perst_gpio = devm_fwnode_gpiod_get(dev,
> of_fwnode_handle(pcie_port_node),
> > +                                              "reset", GPIOD_OUT_HIGH, NULL);
> > +     if (IS_ERR(pcie->perst_gpio)) {
> > +             if (PTR_ERR(pcie->perst_gpio) != -ENOENT) {
> > +                     of_node_put(pcie_port_node);
> > +                     return dev_err_probe(dev, PTR_ERR(pcie->perst_gpio),
> > +                                          "Failed to request reset GPIO\n");
> > +             }
> > +             pcie->perst_gpio = NULL;
> > +     }
> > +
> > +     of_node_put(pcie_port_node);
> > +
> > +     return 0;
> > +}
> > +
> >  static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
> >                                struct platform_device *pdev)
> >  {
> > @@ -426,6 +456,14 @@ static int amd_mdb_add_pcie_port(struct
> amd_mdb_pcie *pcie,
> >
> >       pp->ops = &amd_mdb_pcie_host_ops;
> >
> > +     if (pcie->perst_gpio) {
> > +             mdelay(PCIE_T_PVPERL_MS);
> > +
> > +             /* Deassert the reset signal */
> > +             gpiod_set_value_cansleep(pcie->perst_gpio, 0);
> > +             mdelay(PCIE_T_RRS_READY_MS);
> > +     }
> > +
> >       err = dw_pcie_host_init(pp);
> >       if (err) {
> >               dev_err(dev, "Failed to initialize host, err=%d\n", err);
> > @@ -444,6 +482,7 @@ static int amd_mdb_pcie_probe(struct platform_device
> *pdev)
> >       struct device *dev = &pdev->dev;
> >       struct amd_mdb_pcie *pcie;
> >       struct dw_pcie *pci;
> > +     int ret;
> >
> >       pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> >       if (!pcie)
> > @@ -454,6 +493,10 @@ static int amd_mdb_pcie_probe(struct platform_device
> *pdev)
> >
> >       platform_set_drvdata(pdev, pcie);
> >
> > +     ret = amd_mdb_parse_pcie_port(pcie);
> > +     if (ret)
> > +             return ret;
> > +
> >       return amd_mdb_add_pcie_port(pcie, pdev);
> >  }
> >
> > --
> > 2.43.0
> >

Thanks,
Sai krishna