Re: [PATCH v4] PCI/PM: Skip resuming to D0 if disconnected

[Lukas Wunner <lukas@wunner.de>]

[cc += Rafael, Mika]

On Mon, Jun 23, 2025 at 02:13:34PM -0500, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> 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>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

Reviewed-by: Lukas Wunner <lukas@wunner.de>

> ---
> v4:
>  * no info message
> v3:
>  * Adjust text and subject
>  * Add an info message instead
> v2:
>  * Use pci_dev_is_disconnected()
> v1: https://lore.kernel.org/linux-usb/20250609020223.269407-1-superm1@kernel.org/T/#mf95c947990d016fbfccfd11afe60b8ae08aafa0b
> ---
>  drivers/pci/pci.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 9e42090fb1089..160a9a482c732 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",
> -- 
> 2.43.0