linux-kernel - Re: [PATCH v3 3/3] eeprom: at24: enable runtime pm support

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Message-ID: <20170830124122.3oipo4ykpzmkzdy2@valkosipuli.retiisi.org.uk>
Date:   Wed, 30 Aug 2017 15:41:23 +0300
From:   Sakari Ailus <sakari.ailus@....fi>
To:     "Mohandass, Divagar" <divagar.mohandass@...el.com>
Cc:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "wsa@...-dreams.de" <wsa@...-dreams.de>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Mani, Rajmohan" <rajmohan.mani@...el.com>
Subject: Re: [PATCH v3 3/3] eeprom: at24: enable runtime pm support

On Wed, Aug 30, 2017 at 12:32:07PM +0000, Mohandass, Divagar wrote:
> >> @@ -743,6 +770,15 @@ static int at24_probe(struct i2c_client *client,
> >> const struct i2c_device_id *id)
> >>
> >>  	i2c_set_clientdata(client, at24);
> >>
> >> +	/* enable runtime pm */
> >> +	pm_runtime_get_noresume(&client->dev);
> >> +	err = pm_runtime_set_active(&client->dev);
> >> +	if (err < 0)
> >> +		goto err_clients;
> >> +
> >> +	pm_runtime_enable(&client->dev);
> >> +	pm_runtime_put(&client->dev);
> >> +
> >
> >You're just about to perform a read here. I believe you should move the last
> >put after that.
> 
> At the end of at24_read we are performing a pm_runtime_put, still we need this change ?

True, so this isn't an actual problem.

It'll still power the chip down when you're about to need it, so it'd make
sense to perform the check before pm_runtime_put().

I might move the runtime PM setup after the check altogether.

-- 
Sakari Ailus
e-mail: sakari.ailus@....fi