linux-kernel - Re: [PATCH v3 78/79] media: rcar-vin: use pm_runtime_resume_and

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Message-ID: <20210428081602.68a0d82f@coco.lan>
Date:   Wed, 28 Apr 2021 08:16:02 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     Niklas Söderlund 
        <niklas.soderlund@...natech.se>
Cc:     linuxarm@...wei.com, mauro.chehab@...wei.com,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v3 78/79] media: rcar-vin: use
 pm_runtime_resume_and_get()

Hi Niklas,

Em Tue, 27 Apr 2021 22:12:30 +0200
Niklas Söderlund <niklas.soderlund@...natech.se> escreveu:

> Hi Mauro,
> 
> On 2021-04-27 12:27:08 +0200, Mauro Carvalho Chehab wrote:
> > Commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> > added pm_runtime_resume_and_get() in order to automatically handle
> > dev->power.usage_count decrement on errors.
> > 
> > Use the new API, in order to cleanup the error check logic.
> > 
> > Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> > ---
> >  drivers/media/platform/rcar-vin/rcar-csi2.c | 6 ++++++
> >  drivers/media/platform/rcar-vin/rcar-dma.c  | 6 ++----
> >  drivers/media/platform/rcar-vin/rcar-v4l2.c | 6 ++----
> >  3 files changed, 10 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > index e06cd512aba2..ce8e84f9e3d9 100644
> > --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> > +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> > @@ -408,6 +408,12 @@ static void rcsi2_enter_standby(struct rcar_csi2 *priv)
> >  
> >  static void rcsi2_exit_standby(struct rcar_csi2 *priv)
> >  {
> > +	/*
> > +	 * The code at rcsi2_enter_standby() assumes
> > +	 * inconditionally that PM runtime usage count was
> > +	 * incremented. So, it shouldn't use pm_runtime_resume_and_get()
> > +	 * here.
> > +	 */  
> 
>  	pm_runtime_get_sync(priv->dev);
>
> I think this comment is a bit much. I won't object if you really want to 
> keep it but my preference would be to drop it.

Hmm... I guess we could do this, instead:


diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
index e06cd512aba2..1fc2e6f4b607 100644
--- a/drivers/media/platform/rcar-vin/rcar-csi2.c
+++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
@@ -406,9 +406,14 @@ static void rcsi2_enter_standby(struct rcar_csi2 *priv)
        pm_runtime_put(priv->dev);
 }
 
-static void rcsi2_exit_standby(struct rcar_csi2 *priv)
+static int rcsi2_exit_standby(struct rcar_csi2 *priv)
 {
-       pm_runtime_get_sync(priv->dev);
+       int ret;
+
+       ret = pm_runtime_resume_and_get(priv->dev);
+       if (ret < 0)
+               return ret;
+
        reset_control_deassert(priv->rstc);
 }
 
@@ -657,7 +662,9 @@ static int rcsi2_start(struct rcar_csi2 *priv)
 {
        int ret;
 
-       rcsi2_exit_standby(priv);
+       ret = rcsi2_exit_standby(priv);
+       if (ret < 0)
+               return ret;
 
        ret = rcsi2_start_receiver(priv);
        if (ret) {

Thanks,
Mauro