On Wed, 10 Jul 2024, superm1@xxxxxxxxxx wrote:
> From: Mario Limonciello <mario.limonciello@xxxxxxx>
>
> It is reported that USB4 routers and downstream devices may behave
> incorrectly if a dock cable is plugged in at approximately the time that
> the autosuspend_delay is configured. In this situation the device has
> attempted to enter D3cold, but didn't finish D3cold entry when the PCI
> core tried to transition it back to D0.
>
> Empirically measuring this situation an "aborted" D3cold exit takes
> ~60ms and a "normal" D3cold exit takes ~10ms.
>
> The PCI-PM 1.2 spec specifies that the restore time for functions
> in D3cold is either 'Full context restore or boot latency'.
>
> As PCIe r6.0 sec 5.8 specifies that the device will have gone
> through a conventional reset it may take some time for the
I'd add comma after reset.
The code change looks okay though,
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> device to be ready.
>
> Wait up to 1 sec as specified in PCIe r6.0 sec 6.6.1 for a device
> in D3cold to return to D0.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> drivers/pci/pci.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 4ad02ad640518..9af324ab6bb02 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1388,6 +1388,17 @@ int pci_power_up(struct pci_dev *dev)
> else if (state == PCI_D2)
> udelay(PCI_PM_D2_DELAY);
>
> + /*
> + * D3cold -> D0 will have gone through a conventional reset and may need
> + * time to be ready.
> + */
> + if (dev->current_state == PCI_D3cold) {
> + int ret;
> +
> + ret = pci_dev_wait(dev, "D3cold->D0", PCI_RESET_WAIT);
> + if (ret)
> + return ret;
> + }
> end:
> dev->current_state = PCI_D0;
> if (need_restore)
>
--
i.
