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

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Date:   Tue, 26 May 2020 15:25:36 +0200
From:   Alain Volmat <alain.volmat@...com>
To:     <dinghao.liu@....edu.cn>
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

On Tue, May 26, 2020 at 09:00:23PM +0800, dinghao.liu@....edu.cn wrote:
> 
> > 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.

Thanks, you might want to add a Fixes: tag in your commit message as well.

> 
> > 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