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

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Message-ID: <1461241760.6620.315.camel@linux.intel.com>
Date:	Thu, 21 Apr 2016 15:29:20 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Jisheng Zhang <jszhang@...vell.com>, jarkko.nikula@...ux.intel.com,
	mika.westerberg@...ux.intel.com, wsa@...-dreams.de
Cc:	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
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 <jszhang@...vell.com>

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 <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy