Re: [PATCH 1/4] exynos4-is: Clear isp-i2c adapter power.ignore_children flag

[Wolfram Sang <wsa@the-dreams.de>]

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On Thu, Sep 01, 2016 at 01:39:16PM +0200, Sylwester Nawrocki wrote:
> Since commit 04f59143b571161d25315dd52d7a2ecc022cb71a
> ("i2c: let I2C masters ignore their children for PM")
> the power.ignore_children flag is set when registering an I2C
> adapter. Since I2C transfers are not managed by the fimc-isp-i2c
> driver its clients use pm_runtime_* calls directly to communicate
> required power state of the bus controller.
> However when the power.ignore_children flag is set that doesn't
> work, so clear that flag back after registering the adapter.
> While at it drop pm_runtime_enable() call on the i2c_adapter
> as it is already done by the I2C subsystem when registering
> I2C adapter.
> 
> Cc: <stable@vger.kernel.org> # 4.7+
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

CCing the authors of the "offending" commit as well as linux-pm for more
PM expertise.

> ---
>  drivers/media/platform/exynos4-is/fimc-is-i2c.c | 25 ++++++++++++++++++-------
>  1 file changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/platform/exynos4-is/fimc-is-i2c.c b/drivers/media/platform/exynos4-is/fimc-is-i2c.c
> index 7521aa5..03b4246 100644
> --- a/drivers/media/platform/exynos4-is/fimc-is-i2c.c
> +++ b/drivers/media/platform/exynos4-is/fimc-is-i2c.c
> @@ -55,26 +55,37 @@ static int fimc_is_i2c_probe(struct platform_device *pdev)
>  	i2c_adap->algo = &fimc_is_i2c_algorithm;
>  	i2c_adap->class = I2C_CLASS_SPD;
>  
> +	platform_set_drvdata(pdev, isp_i2c);
> +	pm_runtime_enable(&pdev->dev);
> +
>  	ret = i2c_add_adapter(i2c_adap);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "failed to add I2C bus %s\n",
>  						node->full_name);
> -		return ret;
> +		goto err_pm_dis;
>  	}
>  
> -	platform_set_drvdata(pdev, isp_i2c);
> -
> -	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_enable(&i2c_adap->dev);
> -
> +	/*
> +	 * Client drivers of this adapter don't do any I2C transfers as that
> +	 * is handled by the ISP firmware.  But we rely on the runtime PM
> +	 * state propagation from the clients up to the adapter driver so
> +	 * clear the ignore_children flags here.  PM rutnime calls are not
> +	 * used in probe() handler of clients of this adapter so there is
> +	 * no issues with clearing the flag right after registering the I2C
> +	 * adapter.
> +	 */
> +	pm_suspend_ignore_children(&i2c_adap->dev, false);
>  	return 0;
> +
> +err_pm_dis:
> +	pm_runtime_disable(&pdev->dev);
> +	return ret;
>  }
>  
>  static int fimc_is_i2c_remove(struct platform_device *pdev)
>  {
>  	struct fimc_is_i2c *isp_i2c = platform_get_drvdata(pdev);
>  
> -	pm_runtime_disable(&isp_i2c->adapter.dev);
>  	pm_runtime_disable(&pdev->dev);
>  	i2c_del_adapter(&isp_i2c->adapter);
>  
> -- 
> 1.9.1
> 

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