Re: [PATCH v2 2/3] PCI: qcom: Check for the presence of a device instead of Link up during suspend

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Nov 07, 2025 at 10:13:18AM +0530, Manivannan Sadhasivam wrote:
> The suspend handler checks for the PCIe Link up to decide when to turn off
> the controller resources. But this check is racy as the PCIe Link can go
> down just after this check.
> 
> So use the newly introduced API, pci_root_ports_have_device() that checks
> for the presence of a device under any of the Root Ports to replace the
> Link up check.

Why is pci_root_ports_have_device() itself not racy?

> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 805edbbfe7eb..b2b89e2e4916 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -2018,6 +2018,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>  static int qcom_pcie_suspend_noirq(struct device *dev)
>  {
>  	struct qcom_pcie *pcie;
> +	struct dw_pcie_rp *pp;
>  	int ret = 0;
>  
>  	pcie = dev_get_drvdata(dev);
> @@ -2053,8 +2054,9 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
>  	 * powerdown state. This will affect the lifetime of the storage devices
>  	 * like NVMe.
>  	 */
> -	if (!dw_pcie_link_up(pcie->pci)) {
> -		qcom_pcie_host_deinit(&pcie->pci->pp);
> +	pp = &pcie->pci->pp;
> +	if (!pci_root_ports_have_device(pp->bridge->bus)) {
> +		qcom_pcie_host_deinit(pp);
>  		pcie->suspended = true;
>  	}
>  
> -- 
> 2.48.1
>