linux-kernel - Re: [PATCH] usb: dwc3: remove 'pm_runtime_set

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Message-ID: <20210317082520.GB138912@rack03>
Date:   Wed, 17 Mar 2021 17:25:20 +0900
From:   taehyun cho <taehyun.cho@...sung.com>
To:     Alan Stern <stern@...land.harvard.edu>
Cc:     balbi@...nel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        taehyun.cho@...sung.com
Subject: Re: [PATCH] usb: dwc3: remove 'pm_runtime_set_active' in resume
 callback

On Mon, Mar 15, 2021 at 10:13:35AM -0400, Alan Stern wrote:
> On Mon, Mar 15, 2021 at 04:43:17PM +0900, taehyun cho wrote:
> > 'pm_runtime_set_active' sets a flag to describe rumtime status.
> > This flag is automatically set in pm_runtime_get_sync/put_sync API.
> > 'pm_runtime_set_active' checks the runtime status of parent device.
> > As a result, the below error message is printed.
> > dwc3 11110000.dwc3: runtime PM trying to activate child device
> > 11110000.dwc3 but parent (11110000.usb) is not active.
> 
> This is very suspicious.  That error message indicates a real error is 
> present; removing these pm_runtime_set_active calls won't fix the error.
> 
> You need to determine why the parent platform device 11110000.usb isn't 
> active when the dwc3 probe and resume routines are called.  It seems 
> likely that there is a bug in the platform device's driver.
> 
> Alan Stern
>

Alan,

Thanks to your comments, I checked our platform device driver and found
the problem. Our parent platform device didn't set active in resume
callback. This made a problem. Thank you for the help and sorry for
disturbing you.

Taehyun Cho

> > Signed-off-by: taehyun cho <taehyun.cho@...sung.com>
> > ---
> >  drivers/usb/dwc3/core.c | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index 94fdbe502ce9..e7c0e390f885 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -1553,7 +1553,6 @@ static int dwc3_probe(struct platform_device *pdev)
> >  
> >  	spin_lock_init(&dwc->lock);
> >  
> > -	pm_runtime_set_active(dev);
> >  	pm_runtime_use_autosuspend(dev);
> >  	pm_runtime_set_autosuspend_delay(dev, DWC3_DEFAULT_AUTOSUSPEND_DELAY);
> >  	pm_runtime_enable(dev);
> > @@ -1920,7 +1919,6 @@ static int dwc3_resume(struct device *dev)
> >  		return ret;
> >  
> >  	pm_runtime_disable(dev);
> > -	pm_runtime_set_active(dev);
> >  	pm_runtime_enable(dev);
> >  
> >  	return 0;
> > -- 
> > 2.26.0
>