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From: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: linuxarm@huawei.com, mauro.chehab@huawei.com,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org,
	linux-media@vger.kernel.org, linux-tegra@vger.kernel.org
Subject: Re: [PATCH 17/78] staging: media: vde: use pm_runtime_resume_and_get()
Date: Tue, 27 Apr 2021 11:22:50 +0200	[thread overview]
Message-ID: <20210427112250.5d40c4f4@coco.lan> (raw)
In-Reply-To: <2349831b-e7cd-d38d-fc19-5fabf06f773e@gmail.com>

Hi Dmitry,

Em Sat, 24 Apr 2021 10:35:22 +0300
Dmitry Osipenko <digetx@gmail.com> escreveu:

> 24.04.2021 09:44, Mauro Carvalho Chehab пишет:
> > 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.
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > ---
> >  drivers/staging/media/tegra-vde/vde.c | 16 ++++++++++------
> >  1 file changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/staging/media/tegra-vde/vde.c b/drivers/staging/media/tegra-vde/vde.c
> > index 28845b5bafaf..8936f140a246 100644
> > --- a/drivers/staging/media/tegra-vde/vde.c
> > +++ b/drivers/staging/media/tegra-vde/vde.c
> > @@ -775,9 +775,9 @@ static int tegra_vde_ioctl_decode_h264(struct tegra_vde *vde,
> >  	if (ret)
> >  		goto release_dpb_frames;
> >  
> > -	ret = pm_runtime_get_sync(dev);
> > +	ret = pm_runtime_resume_and_get(dev);
> >  	if (ret < 0)
> > -		goto put_runtime_pm;
> > +		goto unlock;
> >  
> >  	/*
> >  	 * We rely on the VDE registers reset value, otherwise VDE
> > @@ -843,6 +843,8 @@ static int tegra_vde_ioctl_decode_h264(struct tegra_vde *vde,
> >  put_runtime_pm:
> >  	pm_runtime_mark_last_busy(dev);
> >  	pm_runtime_put_autosuspend(dev);
> > +
> > +unlock:
> >  	mutex_unlock(&vde->lock);
> >  
> >  release_dpb_frames:
> > @@ -1069,8 +1071,8 @@ static int tegra_vde_probe(struct platform_device *pdev)
> >  	 * power-cycle it in order to put hardware into a predictable lower
> >  	 * power state.
> >  	 */
> > -	pm_runtime_get_sync(dev);
> > -	pm_runtime_put(dev);
> > +	if (pm_runtime_resume_and_get(dev) >= 0)
> > +		pm_runtime_put(dev);
> >  
> >  	return 0;
> >  
> > @@ -1088,8 +1090,9 @@ static int tegra_vde_remove(struct platform_device *pdev)
> >  {
> >  	struct tegra_vde *vde = platform_get_drvdata(pdev);
> >  	struct device *dev = &pdev->dev;
> > +	int ret;
> >  
> > -	pm_runtime_get_sync(dev);
> > +	ret = pm_runtime_resume_and_get(dev);
> >  	pm_runtime_dont_use_autosuspend(dev);
> >  	pm_runtime_disable(dev);
> >  
> > @@ -1097,7 +1100,8 @@ static int tegra_vde_remove(struct platform_device *pdev)
> >  	 * Balance RPM state, the VDE power domain is left ON and hardware
> >  	 * is clock-gated. It's safe to reboot machine now.
> >  	 */
> > -	pm_runtime_put_noidle(dev);
> > +	if (ret >= 0)
> > +		pm_runtime_put_noidle(dev);
> >  	clk_disable_unprepare(vde->clk);
> >  
> >  	misc_deregister(&vde->miscdev);
> >   
> 
> Hello Mauro,
> 
> Thank you very much for the patch. It looks to me that the original
> variant was a bit simpler, this patch adds more code lines without
> changing the previous behaviour. Or am I missing something?

While on several places the newer code is simpler, the end goal here is
to replace all occurrences of pm_runtime_get_sync() from the media 
subsystem, due to the number of problems we're having with this:

1. despite its name, this is actually a PM runtime resume call,
   but some developers didn't seem to realize that, as I got this
   pattern on some drivers:

        pm_runtime_get_sync(&client->dev);
        pm_runtime_disable(&client->dev);
        pm_runtime_set_suspended(&client->dev);
        pm_runtime_put_noidle(&client->dev);

   It makes no sense to resume PM just to suspend it again ;-)

   The name of the new variant is a lot clearer:
	pm_runtime_resume_and_get()

2. Usual *_get() methods only increment their use count on success,
   but pm_runtime_get_sync() increments it unconditionally. Due to
   that, several drivers were mistakenly not calling
   pm_runtime_put_noidle() when it fails;

3. Consistency: we did similar changes subsystem wide with
   for instance strlcpy() and strcpy() that got replaced by
   strscpy(). Having all drivers using the same known-to-be-safe
   methods is a good thing;

4. Prevent newer drivers to copy-and-paste a code that it would
   be easier to break if they don't truly understand what's behind
   the scenes.

Thanks,
Mauro

  reply	other threads:[~2021-04-27  9:23 UTC|newest]

Thread overview: 127+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-24  6:44 [PATCH 00/78] media: use pm_runtime_resume_and_get() instead of pm_runtime_get_sync() Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 01/78] media: atmel: properly get pm_runtime Mauro Carvalho Chehab
2021-04-24  9:36   ` kernel test robot
2021-04-24  6:44 ` [PATCH 02/78] media: marvel-ccic: fix some issues when getting pm_runtime Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 03/78] media: mdk-mdp: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 04/78] media: rcar_fdp1: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 05/78] media: mdk-mdp: " Mauro Carvalho Chehab
2021-04-24 18:23   ` Ezequiel Garcia
2021-04-24  6:44 ` [PATCH 06/78] media: renesas-ceu: " Mauro Carvalho Chehab
2021-04-24  8:11   ` Jacopo Mondi
2021-04-24  6:44 ` [PATCH 07/78] media: s5p: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 08/78] media: am437x:: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 09/78] media: sh_vou: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 10/78] media: sti/hva: use pm_runtime_resume_and_get() Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 11/78] staging: media: rkvdec: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-04-24 23:20   ` Ezequiel Garcia
2021-04-24  6:44 ` [PATCH 12/78] staging: media: atomisp_fops: use pm_runtime_resume_and_get() Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 13/78] staging: media: hantro_drv: " Mauro Carvalho Chehab
2021-04-24 23:23   ` Ezequiel Garcia
2021-04-26 12:33     ` Mauro Carvalho Chehab
2021-04-26 12:42       ` Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 14/78] staging: media: imx7-mipi-csis: " Mauro Carvalho Chehab
2021-04-26 10:11   ` Rui Miguel Silva
2021-04-24  6:44 ` [PATCH 15/78] staging: media: ipu3: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 16/78] staging: media: cedrus_video: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 17/78] staging: media: vde: " Mauro Carvalho Chehab
2021-04-24  7:35   ` Dmitry Osipenko
2021-04-27  9:22     ` Mauro Carvalho Chehab [this message]
2021-04-27 12:34       ` Johan Hovold
2021-04-24  6:44 ` [PATCH 18/78] staging: media: csi: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 19/78] staging: media: vi: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 20/78] media: mtk-vcodec: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 21/78] media: s5p-jpeg: " Mauro Carvalho Chehab
2021-04-27  9:14   ` Sylwester Nawrocki
2021-04-24  6:44 ` [PATCH 22/78] media: delta-v4l2: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 23/78] media: sun8i_rotate: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 24/78] media: i2c: ak7375: use pm_runtime_resume_and_get() Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 25/78] media: i2c: ccs-core: " Mauro Carvalho Chehab
2021-04-25 18:55   ` Sakari Ailus
2021-04-26 14:01     ` Mauro Carvalho Chehab
2021-04-26 14:09       ` Sakari Ailus
2021-04-26 14:16         ` Mauro Carvalho Chehab
2021-04-26 14:29           ` Sakari Ailus
2021-04-26 17:32             ` Mauro Carvalho Chehab
2021-04-27  7:02               ` Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 26/78] media: i2c: dw9714: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 27/78] media: i2c: dw9768: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 28/78] media: i2c: dw9807-vcm: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 29/78] media: i2c: hi556: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 30/78] media: i2c: imx214: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 31/78] media: i2c: imx219: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 32/78] media: i2c: imx258: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 33/78] media: i2c: imx274: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 34/78] media: i2c: imx290: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 35/78] media: i2c: imx319: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 36/78] media: i2c: imx334: " Mauro Carvalho Chehab
2021-04-26  9:06   ` Alessandrelli, Daniele
2021-04-24  6:44 ` [PATCH 37/78] media: i2c: imx355: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 38/78] media: i2c: mt9m001: " Mauro Carvalho Chehab
2021-04-24  8:24   ` Jacopo Mondi
2021-04-24 10:00     ` Johan Hovold
2021-04-26 14:38       ` Mauro Carvalho Chehab
2021-04-27 12:23         ` Johan Hovold
2021-04-28  8:31           ` Mauro Carvalho Chehab
2021-04-28 10:05             ` Johan Hovold
2021-04-28 11:28               ` Mauro Carvalho Chehab
2021-04-28 11:56                 ` Johan Hovold
2021-04-24  6:44 ` [PATCH 39/78] media: i2c: ov02a10: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 40/78] media: i2c: ov13858: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 41/78] media: i2c: ov2659: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 42/78] media: i2c: ov2685: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 43/78] media: i2c: ov2740: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 44/78] media: i2c: ov5647: " Mauro Carvalho Chehab
2021-04-24  8:30   ` Jacopo Mondi
2021-04-24  6:44 ` [PATCH 45/78] media: i2c: ov5648: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 46/78] media: i2c: ov5670: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 47/78] media: i2c: ov5675: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 48/78] media: i2c: ov5695: " Mauro Carvalho Chehab
2021-04-24  6:44 ` [PATCH 49/78] media: i2c: ov7740: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 50/78] media: i2c: ov8856: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 51/78] media: i2c: ov8865: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 52/78] media: i2c: ov9734: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 53/78] media: i2c: tvp5150: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 54/78] media: i2c: video-i2c: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 55/78] media: ipu3: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 56/78] media: coda: " Mauro Carvalho Chehab
2021-04-26  6:53   ` Philipp Zabel
2021-04-24  6:45 ` [PATCH 57/78] media: exynos4-is: " Mauro Carvalho Chehab
2021-04-25 20:57   ` Sylwester Nawrocki
2021-04-26 13:12     ` Mauro Carvalho Chehab
2021-04-27  8:06       ` Sylwester Nawrocki
2021-04-24  6:45 ` [PATCH 58/78] media: exynos-gsc: " Mauro Carvalho Chehab
2021-04-27  8:18   ` Sylwester Nawrocki
2021-04-27  9:30     ` Mauro Carvalho Chehab
2021-04-27  9:42       ` Mauro Carvalho Chehab
2021-04-27 11:50         ` Sylwester Nawrocki
2021-04-28  7:13           ` Mauro Carvalho Chehab
2021-04-28  7:17             ` Mauro Carvalho Chehab
2021-04-28  8:27               ` Sylwester Nawrocki
2021-04-24  6:45 ` [PATCH 59/78] media: mtk-jpeg: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 60/78] media: camss-csid: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 61/78] media: camss-csiphy: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 62/78] media: camss-ispif: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 63/78] media: camss-vfe: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 64/78] media: core: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 65/78] media: pm_helpers: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 66/78] media: vdec: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 67/78] media: venc: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 68/78] media: rcar-fcp: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 69/78] media: rcar-vin: " Mauro Carvalho Chehab
2021-04-24  8:33   ` Niklas Söderlund
2021-04-24  9:12   ` Geert Uytterhoeven
2021-04-26 13:33     ` Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 70/78] media: rga-buf: " Mauro Carvalho Chehab
2021-04-28 17:09   ` Ezequiel Garcia
2021-04-24  6:45 ` [PATCH 71/78] media: rkisp1-capture: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 72/78] media: s3c-camif: " Mauro Carvalho Chehab
2021-04-25 19:36   ` Sylwester Nawrocki
2021-04-24  6:45 ` [PATCH 73/78] media: s5p-mfc: " Mauro Carvalho Chehab
2021-04-27  9:36   ` Sylwester Nawrocki
2021-04-24  6:45 ` [PATCH 74/78] media: bdisp-v4l2: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 75/78] media: stm32: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 76/78] media: sun4i_v4l2: " Mauro Carvalho Chehab
2021-04-24 10:21   ` kernel test robot
2021-04-24  6:45 ` [PATCH 77/78] media: ti-vpe: " Mauro Carvalho Chehab
2021-04-24  6:45 ` [PATCH 78/78] media: vsp1: " Mauro Carvalho Chehab
2021-04-28 10:13 ` [PATCH 00/78] media: use pm_runtime_resume_and_get() instead of pm_runtime_get_sync() Dan Carpenter

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