[PATCH v3 00/79] Address some issues with PM runtime at media subsystem

[PATCH v3 00/79] Address some issues with PM runtime at media subsystem

[Mauro Carvalho Chehab]

During the review of the patches from unm.edu, one of the patterns
I noticed is the amount of patches trying to fix pm_runtime_get_sync()
calls.

After analyzing the feedback from version 1 of this series, I noticed
a few other weird behaviors at the PM runtime resume code. So, this
series start addressing some bugs and issues at the current code.
Then, it gets rid of pm_runtime_get_sync() at the media subsystem
(with 2 exceptions).

It should be noticed that
Commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
added a new method to does a pm_runtime get, which increments
the usage count only on success.

The rationale of getting rid of pm_runtime_get_sync() is:

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 ;-)

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. The name of the new variant is a lot clearer:
	pm_runtime_resume_and_get()
    As its same clearly says that this is a PM runtime resume function,
    that also increments the usage counter on success;

4. 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;

5. 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.

This series replace places  pm_runtime_get_sync(), by calling
pm_runtime_resume_and_get() instead.

This should help to avoid future mistakes like that, as people
tend to use the existing drivers as examples for newer ones.

compile-tested only.

Patches 1 to 7 fix some issues that already exists at the current
PM runtime code;

patches 8 to 20 fix some usage_count problems that still exists
at the media subsystem;

patches 21 to 78 repaces pm_runtime_get_sync() by 
pm_runtime_resume_and_get();

Patch 79 (and a hunk on patch 78) documents the two exceptions
where pm_runtime_get_sync() will still be used for now.

---

v3: - fix a compilation error;
v2: - addressed pointed issues and fixed a few other PM issues.

Mauro Carvalho Chehab (79):
  media: venus: fix PM runtime logic at venus_sys_error_handler()
  media: i2c: ccs-core: return the right error code at suspend
  media: i2c: mt9m001: don't resume at remove time
  media: i2c: ov7740: don't resume at remove time
  media: i2c: video-i2c: don't resume at remove time
  media: exynos-gsc: don't resume at remove time
  media: atmel: properly get pm_runtime
  media: marvel-ccic: fix some issues when getting pm_runtime
  media: mdk-mdp: fix pm_runtime_get_sync() usage count
  media: rcar_fdp1: fix pm_runtime_get_sync() usage count
  media: rga-buf: use pm_runtime_resume_and_get()
  media: renesas-ceu: Properly check for PM errors
  media: s5p: fix pm_runtime_get_sync() usage count
  media: am437x: fix pm_runtime_get_sync() usage count
  media: sh_vou: fix pm_runtime_get_sync() usage count
  media: mtk-vcodec: fix pm_runtime_get_sync() usage count
  media: s5p-jpeg: fix pm_runtime_get_sync() usage count
  media: delta-v4l2: fix pm_runtime_get_sync() usage count
  media: sun8i_rotate: fix pm_runtime_get_sync() usage count
  staging: media: rkvdec: fix pm_runtime_get_sync() usage count
  staging: media: atomisp_fops: use pm_runtime_resume_and_get()
  staging: media: imx7-mipi-csis: use pm_runtime_resume_and_get()
  staging: media: ipu3: use pm_runtime_resume_and_get()
  staging: media: cedrus_video: use pm_runtime_resume_and_get()
  staging: media: vde: use pm_runtime_resume_and_get()
  staging: media: csi: use pm_runtime_resume_and_get()
  staging: media: vi: use pm_runtime_resume_and_get()
  media: i2c: ak7375: use pm_runtime_resume_and_get()
  media: i2c: ccs-core: use pm_runtime_resume_and_get()
  media: i2c: dw9714: use pm_runtime_resume_and_get()
  media: i2c: dw9768: use pm_runtime_resume_and_get()
  media: i2c: dw9807-vcm: use pm_runtime_resume_and_get()
  media: i2c: hi556: use pm_runtime_resume_and_get()
  media: i2c: imx214: use pm_runtime_resume_and_get()
  media: i2c: imx219: use pm_runtime_resume_and_get()
  media: i2c: imx258: use pm_runtime_resume_and_get()
  media: i2c: imx274: use pm_runtime_resume_and_get()
  media: i2c: imx290: use pm_runtime_resume_and_get()
  media: i2c: imx319: use pm_runtime_resume_and_get()
  media: i2c: imx334: use pm_runtime_resume_and_get()
  media: i2c: imx355: use pm_runtime_resume_and_get()
  media: i2c: mt9m001: use pm_runtime_resume_and_get()
  media: i2c: ov02a10: use pm_runtime_resume_and_get()
  media: i2c: ov13858: use pm_runtime_resume_and_get()
  media: i2c: ov2659: use pm_runtime_resume_and_get()
  media: i2c: ov2685: use pm_runtime_resume_and_get()
  media: i2c: ov2740: use pm_runtime_resume_and_get()
  media: i2c: ov5647: use pm_runtime_resume_and_get()
  media: i2c: ov5648: use pm_runtime_resume_and_get()
  media: i2c: ov5670: use pm_runtime_resume_and_get()
  media: i2c: ov5675: use pm_runtime_resume_and_get()
  media: i2c: ov5695: use pm_runtime_resume_and_get()
  media: i2c: ov7740: use pm_runtime_resume_and_get()
  media: i2c: ov8856: use pm_runtime_resume_and_get()
  media: i2c: ov8865: use pm_runtime_resume_and_get()
  media: i2c: ov9734: use pm_runtime_resume_and_get()
  media: i2c: tvp5150: use pm_runtime_resume_and_get()
  media: i2c: video-i2c: use pm_runtime_resume_and_get()
  media: sti/hva: use pm_runtime_resume_and_get()
  media: ipu3: use pm_runtime_resume_and_get()
  media: coda: use pm_runtime_resume_and_get()
  media: exynos4-is: use pm_runtime_resume_and_get()
  media: exynos-gsc: use pm_runtime_resume_and_get()
  media: mtk-jpeg: use pm_runtime_resume_and_get()
  media: camss: use pm_runtime_resume_and_get()
  media: venus: use pm_runtime_resume_and_get()
  media: venus: vdec: use pm_runtime_resume_and_get()
  media: venus: venc: use pm_runtime_resume_and_get()
  media: rcar-fcp: use pm_runtime_resume_and_get()
  media: rkisp1: use pm_runtime_resume_and_get()
  media: s3c-camif: use pm_runtime_resume_and_get()
  media: s5p-mfc: use pm_runtime_resume_and_get()
  media: bdisp-v4l2: use pm_runtime_resume_and_get()
  media: stm32: use pm_runtime_resume_and_get()
  media: sunxi: use pm_runtime_resume_and_get()
  media: ti-vpe: use pm_runtime_resume_and_get()
  media: vsp1: use pm_runtime_resume_and_get()
  media: rcar-vin: use pm_runtime_resume_and_get()
  media: hantro: document the usage of pm_runtime_get_sync()

 drivers/media/cec/platform/s5p/s5p_cec.c      |  5 +++-
 drivers/media/i2c/ak7375.c                    | 10 +------
 drivers/media/i2c/ccs/ccs-core.c              | 18 +++++-------
 drivers/media/i2c/dw9714.c                    | 10 +------
 drivers/media/i2c/dw9768.c                    | 10 +------
 drivers/media/i2c/dw9807-vcm.c                | 10 +------
 drivers/media/i2c/hi556.c                     |  3 +-
 drivers/media/i2c/imx214.c                    |  6 ++--
 drivers/media/i2c/imx219.c                    |  6 ++--
 drivers/media/i2c/imx258.c                    |  6 ++--
 drivers/media/i2c/imx274.c                    |  3 +-
 drivers/media/i2c/imx290.c                    |  6 ++--
 drivers/media/i2c/imx319.c                    |  6 ++--
 drivers/media/i2c/imx334.c                    |  5 ++--
 drivers/media/i2c/imx355.c                    |  6 ++--
 drivers/media/i2c/mt9m001.c                   |  8 ++----
 drivers/media/i2c/ov02a10.c                   |  6 ++--
 drivers/media/i2c/ov13858.c                   |  6 ++--
 drivers/media/i2c/ov2659.c                    |  6 ++--
 drivers/media/i2c/ov2685.c                    |  7 ++---
 drivers/media/i2c/ov2740.c                    |  6 ++--
 drivers/media/i2c/ov5647.c                    |  9 +++---
 drivers/media/i2c/ov5648.c                    |  6 ++--
 drivers/media/i2c/ov5670.c                    |  6 ++--
 drivers/media/i2c/ov5675.c                    |  3 +-
 drivers/media/i2c/ov5695.c                    |  6 ++--
 drivers/media/i2c/ov7740.c                    |  8 ++----
 drivers/media/i2c/ov8856.c                    |  3 +-
 drivers/media/i2c/ov8865.c                    |  6 ++--
 drivers/media/i2c/ov9734.c                    |  3 +-
 drivers/media/i2c/tvp5150.c                   | 16 ++---------
 drivers/media/i2c/video-i2c.c                 | 14 +++-------
 drivers/media/pci/intel/ipu3/ipu3-cio2-main.c |  3 +-
 drivers/media/platform/am437x/am437x-vpfe.c   | 22 +++++++++++----
 drivers/media/platform/atmel/atmel-isc-base.c | 27 +++++++++++++-----
 drivers/media/platform/atmel/atmel-isi.c      | 19 ++++++++++---
 drivers/media/platform/coda/coda-common.c     |  5 ++--
 drivers/media/platform/exynos-gsc/gsc-core.c  |  3 --
 drivers/media/platform/exynos-gsc/gsc-m2m.c   |  2 +-
 .../media/platform/exynos4-is/fimc-capture.c  |  6 ++--
 drivers/media/platform/exynos4-is/fimc-is.c   |  4 +--
 .../platform/exynos4-is/fimc-isp-video.c      |  3 +-
 drivers/media/platform/exynos4-is/fimc-isp.c  |  7 ++---
 drivers/media/platform/exynos4-is/fimc-lite.c |  5 ++--
 drivers/media/platform/exynos4-is/fimc-m2m.c  |  2 +-
 drivers/media/platform/exynos4-is/media-dev.c |  8 ++----
 drivers/media/platform/exynos4-is/mipi-csis.c |  8 ++----
 .../media/platform/marvell-ccic/mcam-core.c   |  9 ++++--
 .../media/platform/mtk-jpeg/mtk_jpeg_core.c   |  4 +--
 drivers/media/platform/mtk-mdp/mtk_mdp_m2m.c  |  6 ++--
 .../platform/mtk-vcodec/mtk_vcodec_dec_pm.c   |  4 +--
 .../media/platform/qcom/camss/camss-csid.c    |  6 ++--
 .../media/platform/qcom/camss/camss-csiphy.c  |  6 ++--
 .../media/platform/qcom/camss/camss-ispif.c   |  6 ++--
 drivers/media/platform/qcom/camss/camss-vfe.c |  5 ++--
 drivers/media/platform/qcom/venus/core.c      | 28 +++++++++++--------
 .../media/platform/qcom/venus/pm_helpers.c    | 10 +++----
 drivers/media/platform/qcom/venus/vdec.c      |  4 +--
 drivers/media/platform/qcom/venus/venc.c      |  5 ++--
 drivers/media/platform/rcar-fcp.c             |  6 ++--
 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 ++--
 drivers/media/platform/rcar_fdp1.c            | 12 ++++++--
 drivers/media/platform/renesas-ceu.c          |  4 +--
 drivers/media/platform/rockchip/rga/rga-buf.c |  3 +-
 drivers/media/platform/rockchip/rga/rga.c     |  4 ++-
 .../platform/rockchip/rkisp1/rkisp1-capture.c |  3 +-
 .../media/platform/s3c-camif/camif-capture.c  |  2 +-
 drivers/media/platform/s3c-camif/camif-core.c |  5 ++--
 drivers/media/platform/s5p-jpeg/jpeg-core.c   |  2 +-
 drivers/media/platform/s5p-mfc/s5p_mfc_pm.c   |  6 ++--
 drivers/media/platform/sh_vou.c               |  6 +++-
 drivers/media/platform/sti/bdisp/bdisp-v4l2.c |  7 +++--
 drivers/media/platform/sti/delta/delta-v4l2.c |  4 +--
 drivers/media/platform/sti/hva/hva-hw.c       | 17 +++++------
 drivers/media/platform/stm32/stm32-dcmi.c     |  5 ++--
 .../platform/sunxi/sun4i-csi/sun4i_v4l2.c     |  6 ++--
 .../sunxi/sun8i-rotate/sun8i_rotate.c         |  2 +-
 drivers/media/platform/ti-vpe/cal-video.c     |  4 ++-
 drivers/media/platform/ti-vpe/cal.c           |  8 ++++--
 drivers/media/platform/ti-vpe/vpe.c           |  4 +--
 drivers/media/platform/vsp1/vsp1_drv.c        |  6 ++--
 .../staging/media/atomisp/pci/atomisp_fops.c  |  6 ++--
 drivers/staging/media/hantro/hantro_drv.c     |  7 +++++
 drivers/staging/media/imx/imx7-mipi-csis.c    |  7 ++---
 drivers/staging/media/ipu3/ipu3.c             |  3 +-
 drivers/staging/media/rkvdec/rkvdec.c         |  2 +-
 .../staging/media/sunxi/cedrus/cedrus_video.c |  6 ++--
 drivers/staging/media/tegra-vde/vde.c         | 16 +++++++----
 drivers/staging/media/tegra-video/csi.c       |  3 +-
 drivers/staging/media/tegra-video/vi.c        |  3 +-
 92 files changed, 298 insertions(+), 335 deletions(-)

-- 
2.30.2

[PATCH v3 25/79] staging: media: vde: use pm_runtime_resume_and_get()

[Mauro Carvalho Chehab]

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);
-- 
2.30.2

[PATCH v3 26/79] staging: media: csi: use pm_runtime_resume_and_get()

[Mauro Carvalho Chehab]

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-video/csi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/staging/media/tegra-video/csi.c b/drivers/staging/media/tegra-video/csi.c
index 033a6935c26d..e938bf4c48b6 100644
--- a/drivers/staging/media/tegra-video/csi.c
+++ b/drivers/staging/media/tegra-video/csi.c
@@ -298,10 +298,9 @@ static int tegra_csi_enable_stream(struct v4l2_subdev *subdev)
 	struct tegra_csi *csi = csi_chan->csi;
 	int ret, err;
 
-	ret = pm_runtime_get_sync(csi->dev);
+	ret = pm_runtime_resume_and_get(csi->dev);
 	if (ret < 0) {
 		dev_err(csi->dev, "failed to get runtime PM: %d\n", ret);
-		pm_runtime_put_noidle(csi->dev);
 		return ret;
 	}
 
-- 
2.30.2

[PATCH v3 27/79] staging: media: vi: use pm_runtime_resume_and_get()

[Mauro Carvalho Chehab]

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-video/vi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/staging/media/tegra-video/vi.c b/drivers/staging/media/tegra-video/vi.c
index 7a09061cda57..1298740a9c6c 100644
--- a/drivers/staging/media/tegra-video/vi.c
+++ b/drivers/staging/media/tegra-video/vi.c
@@ -297,10 +297,9 @@ static int tegra_channel_start_streaming(struct vb2_queue *vq, u32 count)
 	struct tegra_vi_channel *chan = vb2_get_drv_priv(vq);
 	int ret;
 
-	ret = pm_runtime_get_sync(chan->vi->dev);
+	ret = pm_runtime_resume_and_get(chan->vi->dev);
 	if (ret < 0) {
 		dev_err(chan->vi->dev, "failed to get runtime PM: %d\n", ret);
-		pm_runtime_put_noidle(chan->vi->dev);
 		return ret;
 	}
 
-- 
2.30.2

Re: [PATCH v3 25/79] staging: media: vde: use pm_runtime_resume_and_get()

[Dmitry Osipenko]

27.04.2021 13:26, Mauro Carvalho Chehab пишет:
> @@ -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);

Should be cleaner to return error directly here, IMO.

>  	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);

Re: [PATCH v3 25/79] staging: media: vde: use pm_runtime_resume_and_get()

[Mauro Carvalho Chehab]

Em Tue, 27 Apr 2021 14:47:01 +0300
Dmitry Osipenko <digetx@gmail.com> escreveu:

> 27.04.2021 13:26, Mauro Carvalho Chehab пишет:
> > @@ -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);  
> 
> Should be cleaner to return error directly here, IMO.

I double-checked how drivers/base/platform.c deals with non-zero
returns at the .remove method:

	static int platform_remove(struct device *_dev)
	{
	        struct platform_driver *drv = to_platform_driver(_dev->driver);
	        struct platform_device *dev = to_platform_device(_dev);
	
	        if (drv->remove) {
	                int ret = drv->remove(dev);
	
	                if (ret)
	                        dev_warn(_dev, "remove callback returned a non-zero value. This will be ignored.\n");
	        }
	        dev_pm_domain_detach(_dev, true);
	
	        return 0;
	}

Basically, it will print a message but will ignore whatever happens
afterwards.

So, if the driver is changed to return an error there, it will leak
resources.

Thanks,
Mauro

Re: [PATCH v3 25/79] staging: media: vde: use pm_runtime_resume_and_get()

[Dmitry Osipenko]

28.04.2021 10:20, Mauro Carvalho Chehab пишет:
> Em Tue, 27 Apr 2021 14:47:01 +0300
> Dmitry Osipenko <digetx@gmail.com> escreveu:
> 
>> 27.04.2021 13:26, Mauro Carvalho Chehab пишет:
>>> @@ -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);  
>>
>> Should be cleaner to return error directly here, IMO.
> 
> I double-checked how drivers/base/platform.c deals with non-zero
> returns at the .remove method:
> 
> 	static int platform_remove(struct device *_dev)
> 	{
> 	        struct platform_driver *drv = to_platform_driver(_dev->driver);
> 	        struct platform_device *dev = to_platform_device(_dev);
> 	
> 	        if (drv->remove) {
> 	                int ret = drv->remove(dev);
> 	
> 	                if (ret)
> 	                        dev_warn(_dev, "remove callback returned a non-zero value. This will be ignored.\n");
> 	        }
> 	        dev_pm_domain_detach(_dev, true);
> 	
> 	        return 0;
> 	}
> 
> Basically, it will print a message but will ignore whatever happens
> afterwards.
> 
> So, if the driver is changed to return an error there, it will leak
> resources.

Indeed, thank you. But then the pm_runtime_get_sync() should be more
appropriate since this function is specifically made for such cases
where returned value is ignored.

A better option could be better to add a clarifying comment to the code
rather than to change it to a variant which introduces confusion, IMO.