Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Ignored return value of `pci_dev_wait()` masks hardware readiness timeouts
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commit 606c3a6294de4df52ee7dc27a7792cef6c8f72c4
Author: Bjorn Helgaas <helgaas@kernel.org>

PCI: Wait for device readiness after D3hot -> D0uninitialized transition

This commit adds a call to pci_dev_wait() after transitioning a device from
D3hot to D0uninitialized. This ensures the device is ready to accept config
accesses, especially for devices with No_Soft_Reset == 0.

> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 8f7cfcc000901..9d0fc9fbb76a0 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
[ ... ]
> @@ -1341,10 +1351,14 @@ int pci_power_up(struct pci_dev *dev)
>  	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, 0);
>  
>  	/* Mandatory transition delays; see PCI PM 1.2. */
> -	if (state == PCI_D3hot)
> +	if (state == PCI_D3hot) {
>  		pci_dev_d3_sleep(dev);
> -	else if (state == PCI_D2)
> +		if (!(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))
> +			pci_dev_wait(dev, "power up D3hot->D0uninitialized",
> +				     PCIE_RESET_READY_POLL_MS);

Is it safe to ignore the return value of pci_dev_wait() here?

If the device times out or disconnects, pci_dev_wait() returns -ENOTTY. By
ignoring this error, pci_power_up() continues, unconditionally sets
dev->current_state = PCI_D0, and can return success (1 for need_restore).

If pci_power_up() returns success, will callers like pci_back_from_sleep()
execute pci_restore_state() against an unresponsive device, which could
potentially trigger PCIe Master Aborts, AER events, or system crashes?

Should pci_power_up() propagate the error from pci_dev_wait() to prevent
this?

> +	} else if (state == PCI_D2) {
>  		udelay(PCI_PM_D2_DELAY);
> +	}
>  
>  end:
>  	dev->current_state = PCI_D0;

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Sashiko AI review · https://sashiko.dev/#/patchset/20260514153124.404060-1-bhelgaas@google.com?part=1