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

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Message-ID: <20250326-succinct-steadfast-pronghorn-5fcc21@krzk-bin>
Date: Wed, 26 Mar 2025 09:22:52 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Sai Krishna Musham <sai.krishna.musham@....com>
Cc: bhelgaas@...gle.com, lpieralisi@...nel.org, kw@...ux.com, 
	manivannan.sadhasivam@...aro.org, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	cassel@...nel.org, linux-pci@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, michal.simek@....com, bharat.kumar.gogada@....com, 
	thippeswamy.havalige@....com
Subject: Re: [PATCH 2/2] PCI: amd-mdb: Add support for PCIe RP PERST# signal

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@....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