Hi,

On 7/3/2017 4:55 PM, Manu Gautam wrote:
> Driver currently resumes and increments pm usage_count
> of its child device (dwc3 main) from its runtime_resume
> handler. This requires dwc3 runtime_resume to perform
> pm_runtime_put to decrement the pm usage_count. However
> runtime_put from dwc3 happens for non pci drivers
> (e.g. dwc3-if-simple.c) as well which results in dwc3
> pm usage_count becoming negative after couple of
> runtime suspend resume iterations. Fix this by
> performing runtime_get/put from dwc3-pci driver only
> using workqueue.

Felipe, I don't have any platform that uses dwc3-pci, hence couldn't
test. However, with this change I don't see issue of pm usage_count
becoming -ve on my platform that uses dwc3-of-simple.c.
Let me know if this looks fine.

>
> Signed-off-by: Manu Gautam <mgau...@codeaurora.org>
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index fc556a4..87dedb9 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1378,7 +1378,6 @@ static int dwc3_runtime_resume(struct device *dev)
>       }
>  
>       pm_runtime_mark_last_busy(dev);
> -     pm_runtime_put(dev);
>  
>       return 0;
>  }
> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
> index 84a2ceb..e354acc 100644
> --- a/drivers/usb/dwc3/dwc3-pci.c
> +++ b/drivers/usb/dwc3/dwc3-pci.c
> @@ -20,6 +20,7 @@
>  #include <linux/module.h>
>  #include <linux/slab.h>
>  #include <linux/pci.h>
> +#include <linux/workqueue.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/platform_device.h>
>  #include <linux/gpio/consumer.h>
> @@ -61,6 +62,7 @@ struct dwc3_pci {
>       u8 uuid[16];
>  
>       unsigned int has_dsm_for_pm:1;
> +     struct work_struct wakeup_work;
>  };
>  
>  static const struct acpi_gpio_params reset_gpios = { 0, 0, false };
> @@ -174,6 +176,22 @@ static int dwc3_pci_quirks(struct dwc3_pci *dwc)
>       return 0;
>  }
>  
> +#ifdef CONFIG_PM
> +static void dwc3_pci_resume_work(struct work_struct *work)
> +{
> +     struct dwc3_pci *dwc = container_of(work, struct dwc3_pci, wakeup_work);
> +     struct platform_device *dwc3 = dwc->dwc3;
> +     int ret;
> +
> +     ret = pm_runtime_get_sync(&dwc3->dev);
> +     if (ret)
> +             return;
> +
> +     pm_runtime_mark_last_busy(&dwc3->dev);
> +     pm_runtime_put_sync_autosuspend(&dwc3->dev);
> +}
> +#endif
> +
>  static int dwc3_pci_probe(struct pci_dev *pci,
>               const struct pci_device_id *id)
>  {
> @@ -233,6 +251,9 @@ static int dwc3_pci_probe(struct pci_dev *pci,
>       device_set_run_wake(dev, true);
>       pci_set_drvdata(pci, dwc);
>       pm_runtime_put(dev);
> +#ifdef CONFIG_PM
> +     INIT_WORK(&dwc->wakeup_work, dwc3_pci_resume_work);
> +#endif
>  
>       return 0;
>  err:
> @@ -244,6 +265,9 @@ static void dwc3_pci_remove(struct pci_dev *pci)
>  {
>       struct dwc3_pci         *dwc = pci_get_drvdata(pci);
>  
> +#ifdef CONFIG_PM
> +     cancel_work_sync(&dwc->wakeup_work);
> +#endif
>       device_init_wakeup(&pci->dev, false);
>       pm_runtime_get(&pci->dev);
>       platform_device_unregister(dwc->dwc3);
> @@ -319,14 +343,15 @@ static int dwc3_pci_runtime_suspend(struct device *dev)
>  static int dwc3_pci_runtime_resume(struct device *dev)
>  {
>       struct dwc3_pci         *dwc = dev_get_drvdata(dev);
> -     struct platform_device  *dwc3 = dwc->dwc3;
>       int                     ret;
>  
>       ret = dwc3_pci_dsm(dwc, PCI_INTEL_BXT_STATE_D0);
>       if (ret)
>               return ret;
>  
> -     return pm_runtime_get(&dwc3->dev);
> +     queue_work(pm_wq, &dwc->wakeup_work);
> +
> +     return 0;
>  }
>  #endif /* CONFIG_PM */
>  

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