From: dinghao.liu@zju.edu.cn
To: "Linus Walleij" <linus.walleij@linaro.org>
Cc: "Kangjie Lu" <kjlu@umn.edu>,
"Jonathan Cameron" <jic23@kernel.org>,
"Hartmut Knaack" <knaack.h@gmx.de>,
"Lars-Peter Clausen" <lars@metafoo.de>,
"Peter Meerwald-Stadler" <pmeerw@pmeerw.net>,
linux-iio <linux-iio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Re: [PATCH] iio: magnetometer: ak8974: Fix runtime PM imbalance on error
Date: Tue, 26 May 2020 13:14:06 +0800 (GMT+08:00) [thread overview]
Message-ID: <58a22985.cfec2.1724f66f322.Coremail.dinghao.liu@zju.edu.cn> (raw)
In-Reply-To: <CACRpkda9ENYMLZVnTzN2rn9UvsMOWpeDnOhh7zs4ttAJqgipKw@mail.gmail.com>
Hi, Linus
> On Sun, May 24, 2020 at 4:51 AM Dinghao Liu <dinghao.liu@zju.edu.cn> wrote:
>
> > When devm_regmap_init_i2c() returns an error code, a pairing
> > runtime PM usage counter decrement is needed to keep the
> > counter balanced. For error paths after ak8974_set_power(),
> > ak8974_detect() and ak8974_reset(), things are the same.
> >
> > However, When iio_triggered_buffer_setup() returns an error
> > code, we don't need such a decrement because there is already
> > one before this call. Things are the same for other error paths
> > after it.
> >
> > Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
>
> > ak8974->map = devm_regmap_init_i2c(i2c, &ak8974_regmap_config);
> > if (IS_ERR(ak8974->map)) {
> > dev_err(&i2c->dev, "failed to allocate register map\n");
> > + pm_runtime_put_noidle(&i2c->dev);
> > + pm_runtime_disable(&i2c->dev);
> > return PTR_ERR(ak8974->map);
>
> This is correct.
>
> > ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
> > if (ret) {
> > dev_err(&i2c->dev, "could not power on\n");
> > + pm_runtime_put_noidle(&i2c->dev);
> > + pm_runtime_disable(&i2c->dev);
> > goto power_off;
>
> What about just changing this to goto disable_pm;
>
> > ret = ak8974_detect(ak8974);
> > if (ret) {
> > dev_err(&i2c->dev, "neither AK8974 nor AMI30x found\n");
> > + pm_runtime_put_noidle(&i2c->dev);
> > + pm_runtime_disable(&i2c->dev);
> > goto power_off;
>
> goto disable_pm;
>
> > @@ -786,6 +792,8 @@ static int ak8974_probe(struct i2c_client *i2c,
> > ret = ak8974_reset(ak8974);
> > if (ret) {
> > dev_err(&i2c->dev, "AK8974 reset failed\n");
> > + pm_runtime_put_noidle(&i2c->dev);
> > + pm_runtime_disable(&i2c->dev);
>
> goto disable_pm;
>
> > disable_pm:
> > - pm_runtime_put_noidle(&i2c->dev);
> > pm_runtime_disable(&i2c->dev);
> > ak8974_set_power(ak8974, AK8974_PWR_OFF);
>
> Keep the top pm_runtime_put_noidle().
I found that there was already a pm_runtime_put() before
iio_triggered_buffer_setup() (just after pm_runtime_use_autosuspend).
So if we keep the pm_runtime_put_noidle() here, we will have
two pmusage counter decrement. Do you think this is a bug?
Regards,
Dinghao
>
> The ak8974_set_power() call is fine, the power on call does not
> need to happen in balance. Sure it will attempt to write a register
> but so will the power on call.
>
> Yours,
> Linus Walleij
next prev parent reply other threads:[~2020-05-26 5:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-24 2:51 [PATCH] iio: magnetometer: ak8974: Fix runtime PM imbalance on error Dinghao Liu
2020-05-25 12:08 ` Linus Walleij
2020-05-26 5:14 ` dinghao.liu [this message]
2020-05-26 9:31 ` Linus Walleij
2020-05-26 10:05 ` dinghao.liu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=58a22985.cfec2.1724f66f322.Coremail.dinghao.liu@zju.edu.cn \
--to=dinghao.liu@zju.edu.cn \
--cc=jic23@kernel.org \
--cc=kjlu@umn.edu \
--cc=knaack.h@gmx.de \
--cc=lars@metafoo.de \
--cc=linus.walleij@linaro.org \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pmeerw@pmeerw.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).