[PATCH v4] i2c: designware-platdrv: fix unbalanced clk enable and prepare

[PATCH v4] i2c: designware-platdrv: fix unbalanced clk enable and prepare

[Jisheng Zhang]

If i2c_dw_probe() fails, we should disable and unprepare the clock,
otherwise the clock enable and prepare is left unbalanced.

In dw_i2c_plat_remove(), we'd better to not rely on runtime PM to
disable and unprepare the clock since CONFIG_PM may be disabled when
configuring the kernel. So we explicitly disable and unprepare the
clock in dw_i2c_plat_remove() rather than implicitly rely on
pm_runtime_put_sync(). To keep the device usage count balanced, we
call pm_runtime_put_noidle() to decrease the usage count.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 Since v3:
  - use runtime PM rather than rpm in commit msg
  - remove duplicated "(" in commit msg

 Since v2:
 ?- s/clk/clock
 ?- describe why use pm_runtime_put_noidle()
 
 Since v1:
 ?- fix commit msg: "not rely on rpm" rather than "rely on rpm"
 ?- call i2c_dw_plat_prepare_clk after pm_rumtime_disable()
 drivers/i2c/busses/i2c-designware-platdrv.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index d656657..a771781 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -253,8 +253,11 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	}
 
 	r = i2c_dw_probe(dev);
-	if (r && !dev->pm_runtime_disabled)
-		pm_runtime_disable(&pdev->dev);
+	if (r) {
+		if (!dev->pm_runtime_disabled)
+			pm_runtime_disable(&pdev->dev);
+		i2c_dw_plat_prepare_clk(dev, false);
+	}
 
 	return r;
 }
@@ -264,15 +267,16 @@ static int dw_i2c_plat_remove(struct platform_device *pdev)
 	struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
 
 	pm_runtime_get_sync(&pdev->dev);
+	pm_runtime_dont_use_autosuspend(&pdev->dev);
+	if (!dev->pm_runtime_disabled)
+		pm_runtime_disable(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
 
 	i2c_del_adapter(&dev->adapter);
 
 	i2c_dw_disable(dev);
 
-	pm_runtime_dont_use_autosuspend(&pdev->dev);
-	pm_runtime_put_sync(&pdev->dev);
-	if (!dev->pm_runtime_disabled)
-		pm_runtime_disable(&pdev->dev);
+	i2c_dw_plat_prepare_clk(dev, false);
 
 	return 0;
 }
-- 
2.8.1

[PATCH v4] i2c: designware-platdrv: fix unbalanced clk enable and prepare

[Jarkko Nikula]

Hi

On 04/22/2016 11:49 AM, Jisheng Zhang wrote:
> If i2c_dw_probe() fails, we should disable and unprepare the clock,
> otherwise the clock enable and prepare is left unbalanced.
>
> In dw_i2c_plat_remove(), we'd better to not rely on runtime PM to
> disable and unprepare the clock since CONFIG_PM may be disabled when
> configuring the kernel. So we explicitly disable and unprepare the
> clock in dw_i2c_plat_remove() rather than implicitly rely on
> pm_runtime_put_sync(). To keep the device usage count balanced, we
> call pm_runtime_put_noidle() to decrease the usage count.
>
> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---
>   Since v3:
>    - use runtime PM rather than rpm in commit msg
>    - remove duplicated "(" in commit msg
>
>   Since v2:
>    - s/clk/clock
>    - describe why use pm_runtime_put_noidle()
>
>   Since v1:
>    - fix commit msg: "not rely on rpm" rather than "rely on rpm"
>    - call i2c_dw_plat_prepare_clk after pm_rumtime_disable()
>   drivers/i2c/busses/i2c-designware-platdrv.c | 16 ++++++++++------
>   1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index d656657..a771781 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -253,8 +253,11 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>   	}
>
>   	r = i2c_dw_probe(dev);
> -	if (r && !dev->pm_runtime_disabled)
> -		pm_runtime_disable(&pdev->dev);
> +	if (r) {
> +		if (!dev->pm_runtime_disabled)
> +			pm_runtime_disable(&pdev->dev);
> +		i2c_dw_plat_prepare_clk(dev, false);
> +	}
>
>   	return r;
>   }
> @@ -264,15 +267,16 @@ static int dw_i2c_plat_remove(struct platform_device *pdev)
>   	struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
>
>   	pm_runtime_get_sync(&pdev->dev);
> +	pm_runtime_dont_use_autosuspend(&pdev->dev);
> +	if (!dev->pm_runtime_disabled)
> +		pm_runtime_disable(&pdev->dev);
> +	pm_runtime_put_noidle(&pdev->dev);
>
>   	i2c_del_adapter(&dev->adapter);
>
>   	i2c_dw_disable(dev);
>
> -	pm_runtime_dont_use_autosuspend(&pdev->dev);
> -	pm_runtime_put_sync(&pdev->dev);
> -	if (!dev->pm_runtime_disabled)
> -		pm_runtime_disable(&pdev->dev);
> +	i2c_dw_plat_prepare_clk(dev, false);
>
This feels a bit an invasive change to me for unbalanced clock 
enable/disable and I noticed this changes semantics how 
drivers/acpi/acpi_lpss.c devices are shutdown when removing the driver. 
Although I didn't notice does it cause any regression.

Before patch:
1. drivers/base/dd.c: __device_release_driver()
    - pm_runtime_get_sync()
      -> acpi_device_set_power(D0)
         acpi_lpss_restore_ctx()
         dw_i2c_plat_resume()
2. dw_i2c_plat_remove()
    - pm_runtime_dont_use_autosuspend()
      pm_runtime_put_sync()
      -> dw_i2c_plat_suspend()
         acpi_lpss_save_ctx()
         acpi_device_set_power(D3)
3. __device_release_driver() continue
    - dev->pm_domain->dismiss(dev)
      -> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)

After patch:
1. drivers/base/dd.c: __device_release_driver()
  - pm_runtime_get_sync()
    -> acpi_device_set_power(D0)
       acpi_lpss_restore_ctx()
       dw_i2c_plat_resume()
2. dw_i2c_plat_remove()
    - pm_runtime_dont_use_autosuspend()
      pm_runtime_put_noidle()
      * no device suspending and acpi_lpss_save_ctx()
3. __device_release_driver() continue
    - dev->pm_domain->dismiss(dev)
    -> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)
      * powers down here

So after patch there is no acpi_lpss_save_ctx() call but I don't see 
does it cause any issue here. Maybe it's better to track clock only. 
What you think Andy?

-- 
Jarkko

[PATCH v4] i2c: designware-platdrv: fix unbalanced clk enable and prepare

[Andy Shevchenko]

On Fri, 2016-04-22 at 16:59 +0300, Jarkko Nikula wrote:
> Hi
> 
> On 04/22/2016 11:49 AM, Jisheng Zhang wrote:
> > 
> > If i2c_dw_probe() fails, we should disable and unprepare the clock,
> > otherwise the clock enable and prepare is left unbalanced.
> > 
> > In dw_i2c_plat_remove(), we'd better to not rely on runtime PM to
> > disable and unprepare the clock since CONFIG_PM may be disabled when
> > configuring the kernel. So we explicitly disable and unprepare the
> > clock in dw_i2c_plat_remove() rather than implicitly rely on
> > pm_runtime_put_sync(). To keep the device usage count balanced, we
> > call pm_runtime_put_noidle() to decrease the usage count.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > ---
> > ? Since v3:
> > ???- use runtime PM rather than rpm in commit msg
> > ???- remove duplicated "(" in commit msg
> > 
> > ? Since v2:
> > ???- s/clk/clock
> > ???- describe why use pm_runtime_put_noidle()
> > 
> > ? Since v1:
> > ???- fix commit msg: "not rely on rpm" rather than "rely on rpm"
> > ???- call i2c_dw_plat_prepare_clk after pm_rumtime_disable()
> > ? drivers/i2c/busses/i2c-designware-platdrv.c | 16 ++++++++++------
> > ? 1 file changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index d656657..a771781 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -253,8 +253,11 @@ static int dw_i2c_plat_probe(struct
> > platform_device *pdev)
> > ??	}
> > 
> > ??	r = i2c_dw_probe(dev);
> > -	if (r && !dev->pm_runtime_disabled)
> > -		pm_runtime_disable(&pdev->dev);
> > +	if (r) {
> > +		if (!dev->pm_runtime_disabled)
> > +			pm_runtime_disable(&pdev->dev);
> > +		i2c_dw_plat_prepare_clk(dev, false);
> > +	}
> > 
> > ??	return r;
> > ? }
> > @@ -264,15 +267,16 @@ static int dw_i2c_plat_remove(struct
> > platform_device *pdev)
> > ??	struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
> > 
> > ??	pm_runtime_get_sync(&pdev->dev);
> > +	pm_runtime_dont_use_autosuspend(&pdev->dev);
> > +	if (!dev->pm_runtime_disabled)
> > +		pm_runtime_disable(&pdev->dev);
> > +	pm_runtime_put_noidle(&pdev->dev);
> > 
> > ??	i2c_del_adapter(&dev->adapter);
> > 
> > ??	i2c_dw_disable(dev);
> > 
> > -	pm_runtime_dont_use_autosuspend(&pdev->dev);
> > -	pm_runtime_put_sync(&pdev->dev);
> > -	if (!dev->pm_runtime_disabled)
> > -		pm_runtime_disable(&pdev->dev);
> > +	i2c_dw_plat_prepare_clk(dev, false);
> > 
> This feels a bit an invasive change to me for unbalanced clock?
> enable/disable and I noticed this changes semantics how?
> drivers/acpi/acpi_lpss.c devices are shutdown when removing the
> driver.?
> Although I didn't notice does it cause any regression.
> 
> Before patch:
> 1. drivers/base/dd.c: __device_release_driver()
> ????- pm_runtime_get_sync()
> ??????-> acpi_device_set_power(D0)
> ?????????acpi_lpss_restore_ctx()
> ?????????dw_i2c_plat_resume()
> 2. dw_i2c_plat_remove()
> ????- pm_runtime_dont_use_autosuspend()
> ??????pm_runtime_put_sync()
> ??????-> dw_i2c_plat_suspend()
> ?????????acpi_lpss_save_ctx()
> ?????????acpi_device_set_power(D3)
> 3. __device_release_driver() continue
> ????- dev->pm_domain->dismiss(dev)
> ??????-> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)
> 
> After patch:
> 1. drivers/base/dd.c: __device_release_driver()
> ? - pm_runtime_get_sync()
> ????-> acpi_device_set_power(D0)
> ???????acpi_lpss_restore_ctx()
> ???????dw_i2c_plat_resume()
> 2. dw_i2c_plat_remove()
> ????- pm_runtime_dont_use_autosuspend()
> ??????pm_runtime_put_noidle()
> ??????* no device suspending and acpi_lpss_save_ctx()
> 3. __device_release_driver() continue
> ????- dev->pm_domain->dismiss(dev)
> ????-> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)
> ??????* powers down here
> 
> So after patch there is no acpi_lpss_save_ctx() call but I don't see?
> does it cause any issue here. Maybe it's better to track clock only.?
> What you think Andy?

Now it looks like two fixes in one patch. From the commit message I
didn't get the relation between change runtime PM call (one to the
other) and clock (un)preparation.


-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

[PATCH v4] i2c: designware-platdrv: fix unbalanced clk enable and prepare

[Jisheng Zhang]

Dear Andy

On Mon, 25 Apr 2016 12:07:15 +0300 Andy Shevchenko  wrote:

> On Fri, 2016-04-22 at 16:59 +0300, Jarkko Nikula wrote:
> > Hi
> > 
> > On 04/22/2016 11:49 AM, Jisheng Zhang wrote:  
> > > 
> > > If i2c_dw_probe() fails, we should disable and unprepare the clock,
> > > otherwise the clock enable and prepare is left unbalanced.
> > > 
> > > In dw_i2c_plat_remove(), we'd better to not rely on runtime PM to
> > > disable and unprepare the clock since CONFIG_PM may be disabled when
> > > configuring the kernel. So we explicitly disable and unprepare the
> > > clock in dw_i2c_plat_remove() rather than implicitly rely on
> > > pm_runtime_put_sync(). To keep the device usage count balanced, we
> > > call pm_runtime_put_noidle() to decrease the usage count.
> > > 
> > > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > > ---
> > > ? Since v3:
> > > ???- use runtime PM rather than rpm in commit msg
> > > ???- remove duplicated "(" in commit msg
> > > 
> > > ? Since v2:
> > > ???- s/clk/clock
> > > ???- describe why use pm_runtime_put_noidle()
> > > 
> > > ? Since v1:
> > > ???- fix commit msg: "not rely on rpm" rather than "rely on rpm"
> > > ???- call i2c_dw_plat_prepare_clk after pm_rumtime_disable()
> > > ? drivers/i2c/busses/i2c-designware-platdrv.c | 16 ++++++++++------
> > > ? 1 file changed, 10 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> > > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > > index d656657..a771781 100644
> > > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > > @@ -253,8 +253,11 @@ static int dw_i2c_plat_probe(struct
> > > platform_device *pdev)
> > > ??	}
> > > 
> > > ??	r = i2c_dw_probe(dev);
> > > -	if (r && !dev->pm_runtime_disabled)
> > > -		pm_runtime_disable(&pdev->dev);
> > > +	if (r) {
> > > +		if (!dev->pm_runtime_disabled)
> > > +			pm_runtime_disable(&pdev->dev);
> > > +		i2c_dw_plat_prepare_clk(dev, false);
> > > +	}
> > > 
> > > ??	return r;
> > > ? }
> > > @@ -264,15 +267,16 @@ static int dw_i2c_plat_remove(struct
> > > platform_device *pdev)
> > > ??	struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
> > > 
> > > ??	pm_runtime_get_sync(&pdev->dev);
> > > +	pm_runtime_dont_use_autosuspend(&pdev->dev);
> > > +	if (!dev->pm_runtime_disabled)
> > > +		pm_runtime_disable(&pdev->dev);
> > > +	pm_runtime_put_noidle(&pdev->dev);
> > > 
> > > ??	i2c_del_adapter(&dev->adapter);
> > > 
> > > ??	i2c_dw_disable(dev);
> > > 
> > > -	pm_runtime_dont_use_autosuspend(&pdev->dev);
> > > -	pm_runtime_put_sync(&pdev->dev);
> > > -	if (!dev->pm_runtime_disabled)
> > > -		pm_runtime_disable(&pdev->dev);
> > > +	i2c_dw_plat_prepare_clk(dev, false);
> > >   
> > This feels a bit an invasive change to me for unbalanced clock?
> > enable/disable and I noticed this changes semantics how?
> > drivers/acpi/acpi_lpss.c devices are shutdown when removing the
> > driver.?
> > Although I didn't notice does it cause any regression.
> > 
> > Before patch:
> > 1. drivers/base/dd.c: __device_release_driver()
> > ????- pm_runtime_get_sync()
> > ??????-> acpi_device_set_power(D0)
> > ?????????acpi_lpss_restore_ctx()
> > ?????????dw_i2c_plat_resume()
> > 2. dw_i2c_plat_remove()
> > ????- pm_runtime_dont_use_autosuspend()
> > ??????pm_runtime_put_sync()
> > ??????-> dw_i2c_plat_suspend()
> > ?????????acpi_lpss_save_ctx()
> > ?????????acpi_device_set_power(D3)
> > 3. __device_release_driver() continue
> > ????- dev->pm_domain->dismiss(dev)
> > ??????-> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)
> > 
> > After patch:
> > 1. drivers/base/dd.c: __device_release_driver()
> > ? - pm_runtime_get_sync()
> > ????-> acpi_device_set_power(D0)
> > ???????acpi_lpss_restore_ctx()
> > ???????dw_i2c_plat_resume()
> > 2. dw_i2c_plat_remove()
> > ????- pm_runtime_dont_use_autosuspend()
> > ??????pm_runtime_put_noidle()
> > ??????* no device suspending and acpi_lpss_save_ctx()
> > 3. __device_release_driver() continue
> > ????- dev->pm_domain->dismiss(dev)
> > ????-> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)
> > ??????* powers down here
> > 
> > So after patch there is no acpi_lpss_save_ctx() call but I don't see?
> > does it cause any issue here. Maybe it's better to track clock only.?
> > What you think Andy?  
> 
> Now it looks like two fixes in one patch. From the commit message I
> didn't get the relation between change runtime PM call (one to the
> other) and clock (un)preparation.
> 

I'm not sure I got your points. There are two unbalanced clk enable and
prepare issues before the patch:

one is in the i2c_dw_probe() failure path. another is in the remove path when
CONFIG_PM is disabled.

The patch addresses this unbalance.

Thanks,
Jisheng