Re: [PATCH v5 1/3] PCI: host-common: Fix early bus-walk exit in d3cold_possible()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] PME capability detection is still skipped for devices not in D3hot, leaving the fix incomplete for endpoints in D0.
--

commit 6e30f6ce4308da682727250705301b528bde2289
Author: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>

PCI: host-common: Fix early bus-walk exit in d3cold_possible()

This commit addresses an issue in __pci_host_common_d3cold_possible() where 
the bus walk was aborted when a downstream device was found outside of 
PCI_D3hot. By changing the return value to 0 instead of -EOPNOTSUPP, it allows 
the bus walk to continue and check subsequent devices for PME-from-D3cold 
capabilities, which is especially important during shutdown when devices might 
still be in D0.

> diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
> index a23907a875e57..78bc4c8c96564 100644
> --- a/drivers/pci/controller/pci-host-common.c
> +++ b/drivers/pci/controller/pci-host-common.c
> @@ -274,22 +274,19 @@ static int __pci_host_common_d3cold_possible(struct pci_dev *pdev,
>  	if (!pdev->dev.driver && !pci_is_enabled(pdev))
>  		return 0;
>  
> -	if (pdev->current_state != PCI_D3hot)
> -		goto exit;
> +	if (pdev->current_state != PCI_D3hot) {
> +		*flags &= ~PCI_HOST_D3COLD_ALLOWED;
> +		return 0;
> +	}

[Severity: High]
This is a pre-existing issue, but doesn't this early return still skip PME 
capability detection for endpoints in D0?

The commit message notes it is common during shutdown for an endpoint to still
be in D0, and this patch aims to ensure later devices on the bus are visited.
However, for the very device in D0, __pci_host_common_d3cold_possible() will
clear PCI_HOST_D3COLD_ALLOWED and return 0 before it checks device_may_wakeup().

Does this mean a PCIe endpoint in D0 that supports Wakeup/PME from D3cold will
fail to have its PME capabilities recorded, causing its auxiliary power (Vaux)
to be incorrectly turned off during shutdown?

>  
>  	if (device_may_wakeup(&pdev->dev)) {
> -		if (!pci_pme_capable(pdev, PCI_D3cold))
> -			goto exit;
> -		else
> +		if (pci_pme_capable(pdev, PCI_D3cold))
>  			*flags |= PCI_HOST_PME_D3COLD_CAPABLE;
> +		else
> +			*flags &= ~PCI_HOST_D3COLD_ALLOWED;
>  	}
>  
>  	return 0;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260905-shutdown-v5-0-f0c6bafa1d4f@oss.qualcomm.com?part=1