Re: [PATCH RESEND] PCI: amd-mdb: Assert PERST# on shutdown

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Apr 27, 2026 at 05:42:27PM +0530, Sai Krishna Musham wrote:
> Add a shutdown handler for the AMD MDB PCIe host controller that
> asserts the PERST# signal via GPIO before the system powers off or
> reboots. This ensures the connected PCIe endpoint is held in reset
> during shutdown.

I see a few other drivers (dwc/pci-imx6.c, dwc/pcie-fu740.c,
pcie-iproc-platform.c) that do something similar, but it doesn't look
consistent.  *Should* this be consistent across all drivers?

> Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
> ---
>  drivers/pci/controller/dwc/pcie-amd-mdb.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-amd-mdb.c b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> index 7e50e11fbffd..69d21b4727e4 100644
> --- a/drivers/pci/controller/dwc/pcie-amd-mdb.c
> +++ b/drivers/pci/controller/dwc/pcie-amd-mdb.c
> @@ -507,6 +507,14 @@ static int amd_mdb_pcie_probe(struct platform_device *pdev)
>  	return amd_mdb_add_pcie_port(pcie, pdev);
>  }
>  
> +static void amd_mdb_pcie_shutdown(struct platform_device *pdev)
> +{
> +	struct amd_mdb_pcie *pcie = platform_get_drvdata(pdev);
> +
> +	if (pcie->perst_gpio)
> +		gpiod_set_value_cansleep(pcie->perst_gpio, 1);
> +}
> +
>  static const struct of_device_id amd_mdb_pcie_of_match[] = {
>  	{
>  		.compatible = "amd,versal2-mdb-host",
> @@ -521,6 +529,7 @@ static struct platform_driver amd_mdb_pcie_driver = {
>  		.suppress_bind_attrs = true,
>  	},
>  	.probe = amd_mdb_pcie_probe,
> +	.shutdown = amd_mdb_pcie_shutdown,
>  };
>  
>  builtin_platform_driver(amd_mdb_pcie_driver);
> -- 
> 2.43.0
>