linux-kernel - Re: Re: [PATCH] i2c: stm32f7: Fix runtime PM imbalance in stm32f7_i2c_reg

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Message-ID: <7548c995.d205f.1725111d7c4.Coremail.dinghao.liu@zju.edu.cn>
Date:   Tue, 26 May 2020 21:00:23 +0800 (GMT+08:00)
From:   dinghao.liu@....edu.cn
To:     "Alain Volmat" <alain.volmat@...com>
Cc:     kjlu@....edu, "Pierre-Yves MORDRET" <pierre-yves.mordret@...com>,
        "Maxime Coquelin" <mcoquelin.stm32@...il.com>,
        "Alexandre Torgue" <alexandre.torgue@...com>,
        linux-i2c@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH] i2c: stm32f7: Fix runtime PM imbalance in
 stm32f7_i2c_reg_slave


> Overall, there are several other calls to pm_runtime_get_sync within this
> driver, would you like to fix them all at once ?
> 

Sure, I will send a new patch to merge them all.

> On Thu, May 21, 2020 at 03:05:07PM +0800, Dinghao Liu wrote:
> > pm_runtime_get_sync() increments the runtime PM usage counter even
> > the call returns an error code. Thus a pairing decrement is needed
> > on the error handling path to keep the counter balanced.
> > 
> > Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> > ---
> >  drivers/i2c/busses/i2c-stm32f7.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> > index 330ffed011e0..602cf35649c8 100644
> > --- a/drivers/i2c/busses/i2c-stm32f7.c
> > +++ b/drivers/i2c/busses/i2c-stm32f7.c
> > @@ -1767,8 +1767,10 @@ static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
> >  		return ret;
> >  
> >  	ret = pm_runtime_get_sync(dev);
> > -	if (ret < 0)
> > +	if (ret < 0) {
> > +		pm_runtime_put_autosuspend(dev);
> 
> Considering that if we fail here there is a very good chance that this is due
> to the resume failing, pm_runtime_put_noidle would probably make more sense
> since pm_runtime_put_autosuspend will most probably fail as well.
> 

Agree. Thank you for your advice!

Regards.
Dinghao