linux-kernel - Re: [PATCH v2] usb: dwc3: support continuous runtime PM with dual role

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Message-ID: <7a085229-68a7-d700-1781-14225863a228@cogentembedded.com>
Date:   Thu, 19 Mar 2020 12:34:47 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Martin Kepplinger <martin.kepplinger@...i.sm>, balbi@...nel.org
Cc:     gregkh@...uxfoundation.org, rogerq@...com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: dwc3: support continuous runtime PM with dual
 role

Hello!

On 19.03.2020 11:49, Martin Kepplinger wrote:

> The DRD module calls dwc3_set_mode() on role switches, i.e. when a device is
> being pugged in. In order to support continuous runtime power management when

     Plugged? :-)

> plugging in / unplugging a cable, we need to call pm_runtime_get() in this path.
> 
> Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
> ---
> 
> revision history
> ----------------
> v2: move pm_rumtime calls into workqueue (thanks Roger)
>      remove unrelated documentation patch
> 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..0c058b2ac21d 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(dwc->dev);

    Not get_sync()

> +
>   	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)

MBR, Sergei