linux-kernel - Re: [PATCH v3] usb: dwc3: support continuous runtime PM with dual role

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Date:   Sun, 5 Apr 2020 13:43:25 +0200
From:   Martin Kepplinger <martin.kepplinger@...i.sm>
To:     balbi@...nel.org
Cc:     gregkh@...uxfoundation.org, sergei.shtylyov@...entembedded.com,
        rogerq@...com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] usb: dwc3: support continuous runtime PM with dual
 role

On 19.03.20 11:02, Martin Kepplinger wrote:
> The DRD module calls dwc3_set_mode() on role switches, i.e. when a device is
> being plugged in. In order to support continuous runtime power management when
> plugging in / unplugging a cable, we need to call pm_runtime_get_sync() in
> this path.
> 
> Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
> ---
> 
> 
> revision history
> ----------------
> v3: call pm_runtime_get_sync() and fix commit message typo (thanks Sergei)
> v2: move pm_rumtime calls into workqueue (thanks Roger)
>     remove unrelated documentation patch
>     https://lore.kernel.org/linux-usb/7a085229-68a7-d700-1781-14225863a228@cogentembedded.com/T/
> v1: https://lore.kernel.org/linux-usb/ef22f8de-9bfd-c1d5-111c-696f1336dbda@puri.sm/T/
> 
> 
>  drivers/usb/dwc3/core.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 1d85c42b9c67..da93faef74a6 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -121,17 +121,19 @@ static void __dwc3_set_mode(struct work_struct *work)
>  	if (dwc->dr_mode != USB_DR_MODE_OTG)
>  		return;
>  
> +	pm_runtime_get_sync(dwc->dev);
> +
>  	if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_OTG)
>  		dwc3_otg_update(dwc, 0);
>  
>  	if (!dwc->desired_dr_role)
> -		return;
> +		goto out;
>  
>  	if (dwc->desired_dr_role == dwc->current_dr_role)
> -		return;
> +		goto out;
>  
>  	if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev)
> -		return;
> +		goto out;
>  
>  	switch (dwc->current_dr_role) {
>  	case DWC3_GCTL_PRTCAP_HOST:
> @@ -190,6 +192,9 @@ static void __dwc3_set_mode(struct work_struct *work)
>  		break;
>  	}
>  
> +out:
> +	pm_runtime_mark_last_busy(dwc->dev);
> +	pm_runtime_put_autosuspend(dwc->dev);
>  }
>  
>  void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
> 

any objections or other thoughts about this? I'm using it successfully.

thanks,

                           martin