[PATCH v5 5/6] PCI: dwc: Skip PME_Turn_Off message if there is no endpoint connected

[Manivannan Sadhasivam]

On Tue, Sep 02, 2025 at 04:01:50PM +0800, Richard Zhu wrote:
> A chip freeze is observed on i.MX7D when PCIe RC kicks off the PM_PME
> message and no any devices are connected on the port.
> 

Is it because the controller waits indefinitely for the arrival of the
PME_To_Ack response?

> To workaroud such kind of issue, skip PME_Turn_Off message if there is
> no endpoint connected.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu at nxp.com>

Fixes tag is needed and stable list should be CCed.

- Mani

> Reviewed-by: Frank Li <Frank.Li at nxp.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 57a1ba08c427..b303a74b0fd7 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -1008,12 +1008,15 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
>  	u32 val;
>  	int ret;
>  
> -	if (pci->pp.ops->pme_turn_off) {
> -		pci->pp.ops->pme_turn_off(&pci->pp);
> -	} else {
> -		ret = dw_pcie_pme_turn_off(pci);
> -		if (ret)
> -			return ret;
> +	/* Skip PME_Turn_Off message if there is no endpoint connected */
> +	if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_WAIT) {
> +		if (pci->pp.ops->pme_turn_off) {
> +			pci->pp.ops->pme_turn_off(&pci->pp);
> +		} else {
> +			ret = dw_pcie_pme_turn_off(pci);
> +			if (ret)
> +				return ret;
> +		}
>  	}
>  
>  	if (dwc_quirk(pci, QUIRK_NOL2POLL_IN_PM)) {
> -- 
> 2.37.1
> 

-- 
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