Re: [PATCH v6] PCI/PM: Skip resuming to D0 if disconnected

[Mario Limonciello <superm1@kernel.org>]

On 8/11/2025 11:35 AM, Mario Limonciello (AMD) wrote:
> When a USB4 dock is unplugged the PCIe bridge it's connected to will
> issue a "Link Down" and "Card not detected event". The PCI core will
> treat this as a surprise hotplug event and unconfigure all downstream
> devices. This involves setting the device error state to
> `pci_channel_io_perm_failure` which pci_dev_is_disconnected() will check.
> 
> It doesn't make sense to runtime resume disconnected devices to D0 and
> report the (expected) error, so bail early.
> 
> Suggested-by: Lukas Wunner <lukas@wunner.de>
> Reviewed-by: Lukas Wunner <lukas@wunner.de>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Acked-by: Rafael J. Wysocki <rafael@kernel.org>
> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>

Bjorn,

Can you take a look at this one?

> ---
> v6:
>   * rebase on v6.17-rc1
> v5:
>   * Pick up tags, rebase on linux-next
>   * https://lore.kernel.org/linux-pci/20250709205948.3888045-1-superm1@kernel.org/T/#mbd784f786c50a3d1b5ab1833520995c01eae2fd2
> ---
>   drivers/pci/pci.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b0f4d98036cdd..036511f5b2625 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1374,6 +1374,11 @@ int pci_power_up(struct pci_dev *dev)
>   		return -EIO;
>   	}
>   
> +	if (pci_dev_is_disconnected(dev)) {
> +		dev->current_state = PCI_D3cold;
> +		return -EIO;
> +	}
> +
>   	pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
>   	if (PCI_POSSIBLE_ERROR(pmcsr)) {
>   		pci_err(dev, "Unable to change power state from %s to D0, device inaccessible\n",
> 
> base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585