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Message-ID: <5025467a.453b6.178b5a50321.Coremail.dinghao.liu@zju.edu.cn>
Date: Fri, 9 Apr 2021 15:59:53 +0800 (GMT+08:00)
From: dinghao.liu@....edu.cn
To: "Rui Miguel Silva" <rmfrfs@...il.com>
Cc: kjlu@....edu, "Steve Longerbeam" <slongerbeam@...il.com>,
"Philipp Zabel" <p.zabel@...gutronix.de>,
"Mauro Carvalho Chehab" <mchehab@...nel.org>,
"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
"Shawn Guo" <shawnguo@...nel.org>,
"Sascha Hauer" <s.hauer@...gutronix.de>,
"Pengutronix Kernel Team" <kernel@...gutronix.de>,
"Fabio Estevam" <festevam@...il.com>,
"NXP Linux Team" <linux-imx@....com>, linux-media@...r.kernel.org,
linux-staging@...ts.linux.dev,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH] media: imx: imx7-mipi-csis: Fix runtime PM
imbalance in mipi_csis_s_stream
> Hi Liu,
> Thanks for your patch.
>
> On Thu, Apr 08, 2021 at 05:08:27PM +0800, Dinghao Liu wrote:
> > When v4l2_subdev_call() fails, a pairing PM usage counter
> > decrement is needed to keep the counter balanced. It's the
> > same for the following error paths in case 'enable' is on.
> >
> > Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> > ---
> > drivers/staging/media/imx/imx7-mipi-csis.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/media/imx/imx7-mipi-csis.c b/drivers/staging/media/imx/imx7-mipi-csis.c
> > index a01a7364b4b9..2a3fff231a40 100644
> > --- a/drivers/staging/media/imx/imx7-mipi-csis.c
> > +++ b/drivers/staging/media/imx/imx7-mipi-csis.c
> > @@ -627,21 +627,26 @@ static int mipi_csis_s_stream(struct v4l2_subdev *mipi_sd, int enable)
> > return ret;
> > }
> > ret = v4l2_subdev_call(state->src_sd, core, s_power, 1);
> > - if (ret < 0)
> > + if (ret < 0) {
> > + pm_runtime_put_noidle(&state->pdev->dev);
>
> I think here we should go completely pm_runtime_put to call the
> mipi_csis_pm_suspend down the line, right?
>
> > return ret;
> > + }
> > }
> >
> > mutex_lock(&state->lock);
> > if (enable) {
> > if (state->flags & ST_SUSPENDED) {
> > ret = -EBUSY;
> > + pm_runtime_put_noidle(&state->pdev->dev);
>
> since we are in ST_SUSPENDED state, for sure the pm counter was
> already 0.
>
> > goto unlock;
> > }
> >
> > mipi_csis_start_stream(state);
> > ret = v4l2_subdev_call(state->src_sd, video, s_stream, 1);
> > - if (ret < 0)
> > + if (ret < 0) {
> > + pm_runtime_put_noidle(&state->pdev->dev);
>
> here also we need the pm_runtime_put, maybe just changing the unlock
> tag bellow from:
> if (!enable)
> pm_runtime_put(&state->pdev->dev);
>
> to
> if (!enable || (ret < 0))
> pm_runtime_put(&state->pdev->dev);
>
> will not hurt the first case and will complete the suspend routine
> afterward in the second case.
>
This is much clearer, thanks! I will fix this and send a new patch soon.
Regards,
Dinghao
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