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

From: Krzysztof Kozlowski
Date: Wed Mar 26 2025 - 04:23:06 EST


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@xxxxxxx>
> ---
> 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