Re: [PATCH] PCI: Power on bridges before scanning new devices

[Lukas Wunner <lukas@wunner.de>]

Hi Peter,

On Tue, May 24, 2016 at 04:27:44PM +0200, Peter Wu wrote:
> @@ -246,6 +247,28 @@ static int nouveau_dsm_pci_probe(struct pci_dev *pdev)
>  	return retval;
>  }
>  
> +/* Windows 8/8.1/10 do not use DSM to put the device in D3cold state,
> + * instead it disables power resources on the parent PCIe port device. */
> +static bool nouveau_check_pr3(struct pci_dev *dis_dev)
> +{
> +	acpi_handle parent_handle;
> +	struct acpi_device *ad = NULL;
> +
> +	if (ACPI_FAILURE(acpi_get_parent(nouveau_dsm_priv.dhandle,
> +					 &parent_handle))) {
> +		pr_warn("Failed to obtain the parent device\n");
> +		return false;
> +	}
> +
> +	acpi_bus_get_device(parent_handle, &ad);
> +	if (!ad) {
> +		pr_warn("Failed to obtain an ACPI device for handle\n");
> +		return false;
> +	}
> +
> +	return ad->power.flags.power_resources;
> +}
> +

This can be shortened significantly by using pci_upstream_bridge()
and ACPI_HANDLE().

Best regards,

Lukas