Re: [PATCH v5] PCI: Enable runtime pm of the host bridge

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Oct 09, 2024 at 03:20:25PM -0700, Mayank Rana wrote:
> Hi
> 
> It seems that PCIe controller (pcie-starfive.c driver,
> starfive_pcie_probe()) is setting (child device) PCIe host bridge device's
> runtime state as active going through plda_pcie_host_init() ->
> pci_host_probe() before parent i.e. PCIe controller device itself is being
> mark as active.
> 

Actually the pcie-starfive driver is enabling the runtime PM status of the PCIe
controller (parent) *after* its child host bridge. It should be done other way
around as like other PCIe controller drivers and hence the warning. It was not
triggered earlier because the host bridge (child) PM state was inactive. Since
it becomes active after this patch, the warning is getting triggered.

> log is showing below error from pm_runtime_enable() context:
> dev_warn(dev, "Enabling runtime PM for inactive device with active
> children\n");
> 
> Is it possible to try below change to see if it helps ?
> ======
> diff --git a/drivers/pci/controller/plda/pcie-starfive.c
> b/drivers/pci/controller/plda/pcie-starfive.c
> index 0567ec373a3e..10bcd7e2e958 100644
> --- a/drivers/pci/controller/plda/pcie-starfive.c
> +++ b/drivers/pci/controller/plda/pcie-starfive.c
> @@ -404,6 +404,9 @@ static int starfive_pcie_probe(struct platform_device
> *pdev)
>         if (ret)
>                 return ret;
> 
> +       pm_runtime_enable(&pdev->dev);
> +       pm_runtime_get_sync(&pdev->dev);
> +
>         plda->host_ops = &sf_host_ops;
>         plda->num_events = PLDA_MAX_EVENT_NUM;
>         /* mask doorbell event */
> @@ -416,8 +419,6 @@ static int starfive_pcie_probe(struct platform_device
> *pdev)
>         if (ret)
>                 return ret;
> 
> -       pm_runtime_enable(&pdev->dev);
> -       pm_runtime_get_sync(&pdev->dev);
>         platform_set_drvdata(pdev, pcie);
> 
>         return 0;
> 

Thanks Mayank for the fix. This should fix the warning (and hopefully the
lockdep splat). Marek, please let us know if this helps or not.

- Mani

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