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From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: <linuxarm@huawei.com>, <mauro.chehab@huawei.com>,
	"Paul J. Murphy" <paul.j.murphy@intel.com>,
	Daniele Alessandrelli <daniele.alessandrelli@intel.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	<linux-kernel@vger.kernel.org>, <linux-media@vger.kernel.org>,
	Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [PATCH 06/25] media: i2c: imx334: fix the pm runtime get logic
Date: Wed, 5 May 2021 13:26:02 +0100	[thread overview]
Message-ID: <20210505132602.00004b1f@Huawei.com> (raw)
In-Reply-To: <20210505132426.201e9262@coco.lan>

On Wed, 5 May 2021 13:24:26 +0200
Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:

> Em Wed, 5 May 2021 12:10:40 +0100
> Jonathan Cameron <Jonathan.Cameron@Huawei.com> escreveu:
> 
> > On Wed, 5 May 2021 11:41:56 +0200
> > Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:
> >   
> > > The PM runtime get logic is currently broken, as it checks if
> > > ret is zero instead of checking if it is an error code,
> > > as reported by Dan Carpenter.
> > > 
> > > While here, use the pm_runtime_resume_and_get() as added by:
> > > 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. As a bonus, such function
> > > always return zero on success.
> > > 
> > > It should also be noticed that a fail of pm_runtime_get_sync() would
> > > potentially result in a spurious runtime_suspend(), instead of
> > > using pm_runtime_put_noidle().    
> > 
> > Irony here is that pm_runtime_resume_and_get() returns <= 0 so with that
> > function change, you can stick with if (ret) and still be correct.
> > 
> > So only one of the two changes is needed to fix the bug.  
> 
> Yeah, I noticed ;-)
> 
> On media, almost all devices have I2C bus(es), and I2C send/receive functions
> return positive values. So, a good practice is to check for errors with:
> 
> 	if (ret < 0)
> 
> That's why I opted to keep both changes here ;-)

Fair enough.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> Regards,
> Mauro
> 
> > 
> > J  
> > > 
> > > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > Reviewed-by: Daniele Alessandrelli <daniele.alessandrelli@intel.com>
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > > ---
> > >  drivers/media/i2c/imx334.c | 7 ++++---
> > >  1 file changed, 4 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/media/i2c/imx334.c b/drivers/media/i2c/imx334.c
> > > index 047aa7658d21..23f28606e570 100644
> > > --- a/drivers/media/i2c/imx334.c
> > > +++ b/drivers/media/i2c/imx334.c
> > > @@ -717,9 +717,9 @@ static int imx334_set_stream(struct v4l2_subdev *sd, int enable)
> > >  	}
> > >  
> > >  	if (enable) {
> > > -		ret = pm_runtime_get_sync(imx334->dev);
> > > -		if (ret)
> > > -			goto error_power_off;
> > > +		ret = pm_runtime_resume_and_get(imx334->dev);
> > > +		if (ret < 0)
> > > +			goto error_unlock;
> > >  
> > >  		ret = imx334_start_streaming(imx334);
> > >  		if (ret)
> > > @@ -737,6 +737,7 @@ static int imx334_set_stream(struct v4l2_subdev *sd, int enable)
> > >  
> > >  error_power_off:
> > >  	pm_runtime_put(imx334->dev);
> > > +error_unlock:
> > >  	mutex_unlock(&imx334->mutex);
> > >  
> > >  	return ret;    
> >   
> 
> 
> 
> Thanks,
> Mauro


  reply	other threads:[~2021-05-05 12:27 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-05  9:41 [PATCH 00/25] Fix some PM runtime issues at the media subsystem Mauro Carvalho Chehab
2021-05-05  9:41 ` [PATCH 01/25] staging: media: rkvdec: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-05-05 12:23   ` Jonathan Cameron
2021-05-05  9:41 ` [PATCH 02/25] staging: media: imx7-mipi-csis: " Mauro Carvalho Chehab
2021-05-05 11:06   ` Jonathan Cameron
2021-05-05 11:17     ` Mauro Carvalho Chehab
2021-05-05 13:56     ` Rui Miguel Silva
2021-05-05 14:23       ` Mauro Carvalho Chehab
2021-05-05  9:41 ` [PATCH 03/25] media: venus: Rework error fail recover logic Mauro Carvalho Chehab
2021-05-05 11:05   ` Jonathan Cameron
2021-05-05  9:41 ` [PATCH 04/25] media: s5p_cec: decrement usage count if disabled Mauro Carvalho Chehab
2021-05-05 12:24   ` Jonathan Cameron
2021-05-05  9:41 ` [PATCH 05/25] media: i2c: ccs-core: return the right error code at suspend Mauro Carvalho Chehab
2021-05-05 12:24   ` Jonathan Cameron
2021-05-05 12:51   ` Sakari Ailus
2021-05-05  9:41 ` [PATCH 06/25] media: i2c: imx334: fix the pm runtime get logic Mauro Carvalho Chehab
2021-05-05 11:10   ` Jonathan Cameron
2021-05-05 11:24     ` Mauro Carvalho Chehab
2021-05-05 12:26       ` Jonathan Cameron [this message]
2021-05-05  9:41 ` [PATCH 07/25] media: exynos-gsc: don't resume at remove time Mauro Carvalho Chehab
2021-05-05 12:27   ` Jonathan Cameron
2021-05-05  9:41 ` [PATCH 08/25] media: atmel: properly get pm_runtime Mauro Carvalho Chehab
2021-05-05 12:08   ` Jonathan Cameron
2021-06-10  9:04     ` Eugen.Hristev
2021-06-10  9:38       ` Mauro Carvalho Chehab
2021-06-10 12:00         ` Eugen.Hristev
2021-06-16  8:03           ` Mauro Carvalho Chehab
2021-09-06  8:03           ` Mauro Carvalho Chehab
2021-09-06  8:13             ` Eugen.Hristev
2021-09-13 10:26               ` Eugen.Hristev
2021-05-05  9:41 ` [PATCH 09/25] media: hantro: do a PM resume earlier Mauro Carvalho Chehab
2021-05-05 11:34   ` Jonathan Cameron
2021-05-05 13:22   ` Ezequiel Garcia
2021-05-05 13:46     ` Mauro Carvalho Chehab
2021-05-05 14:01       ` Ezequiel Garcia
2021-05-05 14:15         ` Mauro Carvalho Chehab
2021-05-05  9:42 ` [PATCH 10/25] media: marvel-ccic: fix some issues when getting pm_runtime Mauro Carvalho Chehab
2021-05-05  9:42 ` [PATCH 11/25] media: mdk-mdp: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-05-05  9:42 ` [PATCH 12/25] media: rcar_fdp1: simplify error check logic at fdp_open() Mauro Carvalho Chehab
2021-05-05  9:48   ` Sergei Shtylyov
2021-05-05  9:42 ` [PATCH 13/25] media: rcar_fdp1: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-05-05 12:31   ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 14/25] media: renesas-ceu: Properly check for PM errors Mauro Carvalho Chehab
2021-05-05  9:56   ` Jacopo Mondi
2021-05-05  9:42 ` [PATCH 15/25] media: s5p: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-05-05 12:31   ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 16/25] media: am437x: " Mauro Carvalho Chehab
2021-05-05 12:32   ` Jonathan Cameron
2021-05-08 13:01   ` Lad, Prabhakar
2021-05-05  9:42 ` [PATCH 17/25] media: sh_vou: " Mauro Carvalho Chehab
2021-05-05  9:42 ` [PATCH 18/25] media: mtk-vcodec: fix PM runtime get logic Mauro Carvalho Chehab
2021-05-05 12:32   ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 19/25] media: s5p-jpeg: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-05-05 12:33   ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 20/25] media: sti/delta: use pm_runtime_resume_and_get() Mauro Carvalho Chehab
2021-05-05 12:01   ` Jonathan Cameron
2021-05-05 12:33     ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 21/25] media: sunxi: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-05-05  9:42 ` [PATCH 22/25] media: sti/bdisp: " Mauro Carvalho Chehab
2021-05-05 12:34   ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 23/25] media: exynos4-is: " Mauro Carvalho Chehab
2021-05-05 12:20   ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 24/25] media: exynos-gsc: " Mauro Carvalho Chehab
2021-05-05 12:34   ` Jonathan Cameron
2021-05-05  9:42 ` [PATCH 25/25] media: i2c: ccs-core: " Mauro Carvalho Chehab
2021-05-05 10:34   ` Sakari Ailus
2021-05-05 10:57     ` Mauro Carvalho Chehab
2021-05-05 10:58       ` Mauro Carvalho Chehab
2021-05-05 12:35         ` Jonathan Cameron
2021-05-05 14:06           ` Mauro Carvalho Chehab
2021-05-05 16:36             ` Jonathan Cameron
2021-05-05 11:02       ` Sakari Ailus
2021-05-06 15:11 ` [PATCH 00/25] Fix some PM runtime issues at the media subsystem Mauro Carvalho Chehab

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