Re: [PATCH] PCI: Stop waiting for link status after config read failure

[Ilpo Järvinen]

On Fri, 4 Sep 2026, Yury Murashka wrote:

> With a nested PCIe topology with multiple layers of hotplug, a link can go
> down near the bottom of the topology shortly before a link above it goes
> down. In that case, pcie_wait_for_link_status() can wait for the full
> timeout while every read of the link status register fails because the
> device has disappeared.
> 
> Return immediately when reading the link status fails so event processing
> can continue.
> 
> Signed-off-by: Yury Murashka <yurypm@xxxxxxxxxx>
> Co-authored-by: James Sewart <jamessewart@xxxxxxxxxx>
> ---
>  drivers/pci/pci.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b2879a6be..a568d5ac1 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4565,8 +4565,9 @@ static int pci_pm_reset(struct pci_dev *dev, bool probe)
>   * @use_lt: Use the LT bit if TRUE, or the DLLLA bit if FALSE.
>   * @active: Waiting for active or inactive?
>   *
> - * Return 0 if successful, or -ETIMEDOUT if status has not changed within
> - * PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds.
> + * Return 0 if successful, -ENODEV if the link status cannot be read, or
> + * -ETIMEDOUT if status has not changed within PCIE_LINK_RETRAIN_TIMEOUT_MS
> + * milliseconds.
>   */
>  static int pcie_wait_for_link_status(struct pci_dev *pdev,
>  				     bool use_lt, bool active)
> @@ -4580,7 +4581,8 @@ static int pcie_wait_for_link_status(struct pci_dev *pdev,
>  
>  	end_jiffies = jiffies + msecs_to_jiffies(PCIE_LINK_RETRAIN_TIMEOUT_MS);
>  	do {
> -		pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta);
> +		if (pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta))
> +			return -ENODEV;

Wouldn't it be better to base such checks on PCI_POSSIBLE_ERROR()?

If you keep the check for the case where pcie_capability_read_word() 
returns error, its return value should be converted with 
pcibios_err_to_errno(), not just return -ENODEV.

>  		if ((lnksta & lnksta_mask) == lnksta_match)
>  			return 0;
>  		msleep(1);
> @@ -4603,8 +4605,9 @@ static int pcie_wait_for_link_status(struct pci_dev *pdev,
>   * according to @use_lt.  It is not verified whether the use of the DLLLA
>   * bit is valid.
>   *
> - * Return 0 if successful, or -ETIMEDOUT if training has not completed
> - * within PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds.
> + * Return 0 if successful, -ENODEV if the link status cannot be read, or

Kerneldoc wants this formatting:

Return:

> + * -ETIMEDOUT if training has not completed within
> + * PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds.
>   */
>  int pcie_retrain_link(struct pci_dev *pdev, bool use_lt)
>  {
> 
> base-commit: a500db7819c50db59e55f1b4fa1c3baa5a2616f3
> 

-- 
 i.