linux-kernel - Re: [PATCH v3 1/2] i2c: davinci: Add PM Runtime Support

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Message-ID: <57153767-6dee-a5b5-548c-f7b0dc104b46@ti.com>
Date:   Mon, 11 Sep 2017 16:59:10 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Franklin S Cooper Jr <fcooper@...com>, <wsa@...-dreams.de>,
        <robh+dt@...nel.org>, <linux@...linux.org.uk>,
        <linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <grygorii.strashko@...com>,
        <vigneshr@...com>
Subject: Re: [PATCH v3 1/2] i2c: davinci: Add PM Runtime Support

On Friday 08 September 2017 11:24 PM, Franklin S Cooper Jr wrote:
> 66AK2G has I2C instances that are not apart of the ALWAYS_ON power domain
> like other Keystone 2 SoCs and OMAPL138. Therefore, pm_runtime

unlike ?

> is required to insure the power domain used by the specific I2C instance is
> properly turned on along with its functional clock.
> 
> Signed-off-by: Franklin S Cooper Jr <fcooper@...com>
> ---
> Version 3 changes:
> Remove several statements that set clk to NULL
> Fix error path
> 
>  drivers/i2c/busses/i2c-davinci.c | 64 +++++++++++++++++++++++++++++++++-------
>  1 file changed, 53 insertions(+), 11 deletions(-)

> @@ -802,12 +821,22 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>  	dev->clk = devm_clk_get(&pdev->dev, NULL);
>  	if (IS_ERR(dev->clk))
>  		return PTR_ERR(dev->clk);
> -	clk_prepare_enable(dev->clk);
>  
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	dev->base = devm_ioremap_resource(&pdev->dev, mem);
>  	if (IS_ERR(dev->base)) {
> -		r = PTR_ERR(dev->base);
> +		return PTR_ERR(dev->base);
> +	}
> +
> +	pm_runtime_set_autosuspend_delay(dev->dev,
> +					 DAVINCI_I2C_PM_TIMEOUT);
> +	pm_runtime_use_autosuspend(dev->dev);
> +
> +	pm_runtime_enable(dev->dev);
> +
> +	r = pm_runtime_get_sync(dev->dev);
> +	if (r < 0) {
> +		dev_err(dev->dev, "failed to runtime_get device: %d\n", r);
>  		goto err_unuse_clocks;

You end up doing a pm_runtime_put_sync() on failure here, instead of
pm_runtime_put_noidle() like rest of the patch.

May be handle this failure here instead of relying on the goto path.

>  	}
>  
> @@ -849,27 +878,40 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>  	if (r)
>  		goto err_unuse_clocks;
>  
> +	pm_runtime_mark_last_busy(dev->dev);
> +	pm_runtime_put_autosuspend(dev->dev);
> +
>  	return 0;
>  
>  err_unuse_clocks:
> -	clk_disable_unprepare(dev->clk);
> -	dev->clk = NULL;
> +	pm_runtime_dont_use_autosuspend(dev->dev);
> +	pm_runtime_put_sync(dev->dev);
> +	pm_runtime_disable(dev->dev);
> +
>  	return r;
>  }

Thanks,
Sekhar