On Thu, 22 Aug 2024, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
>
> 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 ~6ms.
>
> 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
> 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.
>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> drivers/pci/pci.c | 11 +++++++++++
> drivers/pci/pci.h | 1 +
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b7717155e2fd0..7e861b6923d0a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1425,6 +1425,17 @@ 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, PCI_DEV_WAIT_D3COLD_D0, PCI_RESET_WAIT);
> + if (ret)
> + return ret;
> + }
> end:
> dev->current_state = PCI_D0;
> if (need_restore)
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 477257e843952..a675f5d55f298 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -11,6 +11,7 @@ enum pci_reset_type {
> PCI_DEV_WAIT_BUS_RESET,
> PCI_DEV_WAIT_RESUME,
> PCI_DEV_WAIT_DPC,
> + PCI_DEV_WAIT_D3COLD_D0,
Don't you need to add a string for this too? :-/
I wonder if it would be prudent to add PCI_DEV_WAIT_MAX and
use static_assert() for the sizeof the pci_reset_types[] in patch 1 to
autodetect mismatch (though it won't help if something is added in the
middle of the list).
--
i.