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Date:   Wed, 05 May 2021 14:56:40 +0100
Message-Id: <CB5D4B64QTP4.GBH80G3VX3B6@arch-thunder>
To:     "Jonathan Cameron" <Jonathan.Cameron@Huawei.com>,
        "Mauro Carvalho Chehab" <mchehab+huawei@kernel.org>
Cc:     <linuxarm@huawei.com>, <mauro.chehab@huawei.com>,
        "Fabio Estevam" <festevam@gmail.com>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Mauro Carvalho Chehab" <mchehab@kernel.org>,
        "NXP Linux Team" <linux-imx@nxp.com>,
        "Pengutronix Kernel Team" <kernel@pengutronix.de>,
        "Philipp Zabel" <p.zabel@pengutronix.de>,
        "Sascha Hauer" <s.hauer@pengutronix.de>,
        "Shawn Guo" <shawnguo@kernel.org>,
        "Steve Longerbeam" <slongerbeam@gmail.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <linux-media@vger.kernel.org>,
        <linux-staging@lists.linux.dev>
Subject: Re: [PATCH 02/25] staging: media: imx7-mipi-csis: fix
 pm_runtime_get_sync() usage count
From:   "Rui Miguel Silva" <rmfrfs@gmail.com>
References: <cover.1620207353.git.mchehab+huawei@kernel.org>
 <793a5806a63b6313606fd1c344b9eec41e61a440.1620207353.git.mchehab+huawei@kernel.org> <20210505120652.00001236@Huawei.com>
In-Reply-To: <20210505120652.00001236@Huawei.com>
Precedence: bulk

Hi,
On Wed May 5, 2021 at 12:06 PM WEST, Jonathan Cameron wrote:

> On Wed, 5 May 2021 11:41:52 +0200
> Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:
>
> > The pm_runtime_get_sync() internally increments the
> > dev->power.usage_count without decrementing it, even on errors.
> > Replace it by the new pm_runtime_resume_and_get(), introduced by:
> > commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to dea=
l with usage counter")
> > in order to properly decrement the usage counter, avoiding
> > a potential PM usage counter leak.
> >=20
> > Acked-by: Rui Miguel Silva <rmfrfs@gmail.com>
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
>
> Not a fix as far as I can see, just a cleanup - so perhaps not this set?

yes, the original changelog of this patch, that I acked,  made it
clear it was a cleanup:

"
Commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to
deal with usage counter")                                                  =
                                                                           =
           =20
added pm_runtime_resume_and_get() in order to automatically handle=20
dev->power.usage_count decrement on errors.

Use the new API, in order to cleanup the error check logic.
"

This one above is new, but I saw Mauro is going change it.

------
Cheers,
     Rui

>
> Jonathan
>
>
> > ---
> >  drivers/staging/media/imx/imx7-mipi-csis.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> >=20
> > diff --git a/drivers/staging/media/imx/imx7-mipi-csis.c b/drivers/stagi=
ng/media/imx/imx7-mipi-csis.c
> > index 025fdc488bd6..1dc680d94a46 100644
> > --- a/drivers/staging/media/imx/imx7-mipi-csis.c
> > +++ b/drivers/staging/media/imx/imx7-mipi-csis.c
> > @@ -695,11 +695,10 @@ static int mipi_csis_s_stream(struct v4l2_subdev =
*mipi_sd, int enable)
> > =20
> >  		mipi_csis_clear_counters(state);
> > =20
> > -		ret =3D pm_runtime_get_sync(&state->pdev->dev);
> > -		if (ret < 0) {
> > -			pm_runtime_put_noidle(&state->pdev->dev);
> > +		ret =3D pm_runtime_resume_and_get(&state->pdev->dev);
> > +		if (ret < 0)
> >  			return ret;
> > -		}
> > +
> >  		ret =3D v4l2_subdev_call(state->src_sd, core, s_power, 1);
> >  		if (ret < 0 && ret !=3D -ENOIOCTLCMD)
> >  			goto done;