2016-04-21 11:27:09

by Jisheng Zhang

Subject: [PATCH v3] i2c: designware-platdrv: fix unbalanced clk enable and prepare

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 rpm 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 <[email protected]>
---
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

2016-04-21 12:28:21

by Andy Shevchenko

Subject: Re: [PATCH v3] i2c: designware-platdrv: fix unbalanced clk enable and prepare

On Thu, 2016-04-21 at 19:22 +0800, 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 rpm to disable

Sorry, didn't notice earlier
rpm -> runtime PM

> 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 <[email protected]>

I don't know if Wolfram wants you to send new version, and I dunno if
others still have comments, but

Patch is in a good shape, but I think we have to carefully check the
runtime PM change.

> ---
> 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;
>  }

--
Andy Shevchenko <[email protected]>
Intel Finland Oy