[PATCH 0/2] Add support for AMD Versal2 MDB PCIe RP PERST#

[PATCH 0/2] Add support for AMD Versal2 MDB PCIe RP PERST#

[Sai Krishna Musham]

Add support for PCIe Root Port PERST# signal

Add `reset-gpios` property to AMD Versal2 MDB controller binding.

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

 .../bindings/pci/amd,versal2-mdb-host.yaml    |  2 ++
 drivers/pci/controller/dwc/pcie-amd-mdb.c     | 20 +++++++++++++++++++
 2 files changed, 22 insertions(+)

-- 
2.31.1

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

[Sai Krishna Musham]

Add `reset-gpios` property to enable TCA6416 I2C GPIO expander based
handling of the PCIe PERST# signal.

Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
---
 Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml | 2 ++
 1 file changed, 2 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..e6117d326279 100644
--- a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
+++ b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
@@ -87,6 +87,7 @@ 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 +113,7 @@ examples:
             #size-cells = <2>;
             #interrupt-cells = <1>;
             device_type = "pci";
+            reset-gpios = <&tca6416_u37 7 GPIO_ACTIVE_LOW>;
             pcie_intc_0: interrupt-controller {
                 #address-cells = <0>;
                 #interrupt-cells = <1>;
-- 
2.31.1

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

[Krzysztof Kozlowski]

On Wed, Mar 26, 2025 at 09:45:06AM +0530, Sai Krishna Musham wrote:
> Add `reset-gpios` property to enable TCA6416 I2C GPIO expander based
> handling of the PCIe PERST# signal.

Hm? Where? You just updated example, did not add anything to the
binding. Assuming that is what you wanted, then fix subject and commit
msg to say that you make example complete.

Best regards,
Krzysztof

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

[Sai Krishna Musham]

Add PERST# signal handling via I2C GPIO expander for AMD Versal2
MDB PCIe Root Port.

Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
---
 drivers/pci/controller/dwc/pcie-amd-mdb.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c b/drivers/pci/controller/dwc/pcie-amd-mdb.c
index 4eb2a4e8189d..4eea53e9e197 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
@@ -408,6 +409,7 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
 	struct dw_pcie *pci = &pcie->pci;
 	struct dw_pcie_rp *pp = &pci->pp;
 	struct device *dev = &pdev->dev;
+	struct gpio_desc *reset_gpio;
 	int err;
 
 	pcie->slcr = devm_platform_ioremap_resource_byname(pdev, "slcr");
@@ -426,6 +428,24 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
 
 	pp->ops = &amd_mdb_pcie_host_ops;
 
+	/* Request the GPIO for PCIe reset signal and assert */
+	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(reset_gpio)) {
+		if (PTR_ERR(reset_gpio) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_err(dev, "Failed to request reset GPIO\n");
+		return PTR_ERR(reset_gpio);
+	}
+
+	if (reset_gpio) {
+		/* Controller specific delay */
+		udelay(50);
+
+		/* Deassert the reset signal */
+		gpiod_set_value_cansleep(reset_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);
-- 
2.31.1

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

[Krzysztof Kozlowski]

On Wed, Mar 26, 2025 at 09:45:07AM +0530, Sai Krishna Musham wrote:
> Add PERST# signal handling via I2C GPIO expander for AMD Versal2
> MDB PCIe Root Port.
> 
> Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
> ---
>  drivers/pci/controller/dwc/pcie-amd-mdb.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> index 4eb2a4e8189d..4eea53e9e197 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
> @@ -408,6 +409,7 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
>  	struct dw_pcie *pci = &pcie->pci;
>  	struct dw_pcie_rp *pp = &pci->pp;
>  	struct device *dev = &pdev->dev;
> +	struct gpio_desc *reset_gpio;
>  	int err;
>  
>  	pcie->slcr = devm_platform_ioremap_resource_byname(pdev, "slcr");
> @@ -426,6 +428,24 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie *pcie,
>  
>  	pp->ops = &amd_mdb_pcie_host_ops;
>  
> +	/* Request the GPIO for PCIe reset signal and assert */
> +	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(reset_gpio)) {
> +		if (PTR_ERR(reset_gpio) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +		dev_err(dev, "Failed to request reset GPIO\n");

Do not open-code dev_err_probe.

Best regards,
Krzysztof

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

[Musham, Sai Krishna]

[AMD Official Use Only - AMD Internal Distribution Only]

Hi Krzysztof,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzk@kernel.org>
> Sent: Wednesday, March 26, 2025 1:53 PM
> To: Musham, Sai Krishna <sai.krishna.musham@amd.com>
> Cc: bhelgaas@google.com; lpieralisi@kernel.org; kw@linux.com;
> manivannan.sadhasivam@linaro.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 2/2] PCI: amd-mdb: Add support for PCIe RP PERST# signal
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Wed, Mar 26, 2025 at 09:45:07AM +0530, Sai Krishna Musham wrote:
> > Add PERST# signal handling via I2C GPIO expander for AMD Versal2 MDB
> > PCIe Root Port.
> >
> > Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-amd-mdb.c | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> > index 4eb2a4e8189d..4eea53e9e197 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
> > @@ -408,6 +409,7 @@ static int amd_mdb_add_pcie_port(struct amd_mdb_pcie
> *pcie,
> >       struct dw_pcie *pci = &pcie->pci;
> >       struct dw_pcie_rp *pp = &pci->pp;
> >       struct device *dev = &pdev->dev;
> > +     struct gpio_desc *reset_gpio;
> >       int err;
> >
> >       pcie->slcr = devm_platform_ioremap_resource_byname(pdev,
> > "slcr"); @@ -426,6 +428,24 @@ static int amd_mdb_add_pcie_port(struct
> > amd_mdb_pcie *pcie,
> >
> >       pp->ops = &amd_mdb_pcie_host_ops;
> >
> > +     /* Request the GPIO for PCIe reset signal and assert */
> > +     reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> > +     if (IS_ERR(reset_gpio)) {
> > +             if (PTR_ERR(reset_gpio) == -EPROBE_DEFER)
> > +                     return -EPROBE_DEFER;
> > +             dev_err(dev, "Failed to request reset GPIO\n");
>
> Do not open-code dev_err_probe.
>

Thank you for reviewing. Sure, I will use dev_err_probe in next patch.

> Best regards,
> Krzysztof

Regards,
Sai Krishna