linux-kernel - Re: [PATCH v6 3/6] can: m

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Date:   Tue, 2 Jan 2018 17:07:00 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Faiz Abbas <faiz_abbas@...com>, wg@...ndegger.com,
        robh+dt@...nel.org, mark.rutland@....com
Cc:     linux-can@...r.kernel.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        nsekhar@...com, fcooper@...com, robh@...nel.org,
        Wenyou.Yang@...rochip.com, sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH v6 3/6] can: m_can: Add PM Runtime

On 12/22/2017 02:31 PM, Faiz Abbas wrote:
> From: Franklin S Cooper Jr <fcooper@...com>
> 
> Add support for PM Runtime which is the new way to handle managing clocks.
> However, to avoid breaking SoCs not using PM_RUNTIME leave the old clk
> management approach in place.

There is no PM_RUNTIME anymore since 464ed18ebdb6 ("PM: Eliminate
CONFIG_PM_RUNTIME")

Have a look at the discussion: https://patchwork.kernel.org/patch/9436507/ :

>> Well, I admit it would be nicer if drivers didn't have to worry about 
>> whether or not CONFIG_PM was enabled.  A slightly cleaner approach 
>> from the one outlined above would have the probe routine do this:
>> 
>> 	my_power_up(dev);
>> 	pm_runtime_set_active(dev);
>> 	pm_runtime_get_noresume(dev);
>> 	pm_runtime_enable(dev);

> PM_RUNTIME is required by OMAP based devices to handle clock management.
> Therefore, this allows future Texas Instruments SoCs that have the MCAN IP
> to work with this driver.

Who will set the SET_RUNTIME_PM_OPS in this case?

> Signed-off-by: Franklin S Cooper Jr <fcooper@...com>
> [nsekhar@...com: handle pm_runtime_get_sync() failure, fix some bugs]
> Signed-off-by: Sekhar Nori <nsekhar@...com>
> Signed-off-by: Faiz Abbas <faiz_abbas@...com>
> ---
>  drivers/net/can/m_can/m_can.c | 38 ++++++++++++++++++++++++++++++++++----
>  1 file changed, 34 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index f72116e..53e764f 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -23,6 +23,7 @@
>  #include <linux/of.h>
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/iopoll.h>
>  #include <linux/can/dev.h>
>  
> @@ -625,19 +626,33 @@ static int m_can_clk_start(struct m_can_priv *priv)
>  {
>  	int err;
>  
> +	err = pm_runtime_get_sync(priv->device);
> +	if (err) {
> +		pm_runtime_put_noidle(priv->device);

Why do you call this in case of an error?

> +		return err;
> +	}
> +
>  	err = clk_prepare_enable(priv->hclk);
>  	if (err)
> -		return err;
> +		goto pm_runtime_put;
>  
>  	err = clk_prepare_enable(priv->cclk);
>  	if (err)
> -		clk_disable_unprepare(priv->hclk);
> +		goto disable_hclk;
>  
>  	return err;
> +
> +disable_hclk:
> +	clk_disable_unprepare(priv->hclk);
> +pm_runtime_put:
> +	pm_runtime_put_sync(priv->device);
> +	return err;
>  }
>  
>  static void m_can_clk_stop(struct m_can_priv *priv)
>  {
> +	pm_runtime_put_sync(priv->device);
> +
>  	clk_disable_unprepare(priv->cclk);
>  	clk_disable_unprepare(priv->hclk);
>  }
> @@ -1577,13 +1592,20 @@ static int m_can_plat_probe(struct platform_device *pdev)
>  	/* Enable clocks. Necessary to read Core Release in order to determine
>  	 * M_CAN version
>  	 */
> +	pm_runtime_enable(&pdev->dev);
> +	ret = pm_runtime_get_sync(&pdev->dev);
> +	if (ret)  {
> +		pm_runtime_put_noidle(&pdev->dev);

Why do you call this in case of error?

> +		goto pm_runtime_fail;
> +	}
> +
>  	ret = clk_prepare_enable(hclk);
>  	if (ret)
> -		goto disable_hclk_ret;
> +		goto pm_runtime_put;
>  
>  	ret = clk_prepare_enable(cclk);
>  	if (ret)
> -		goto disable_cclk_ret;
> +		goto disable_hclk_ret;
>  
>  	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "m_can");
>  	addr = devm_ioremap_resource(&pdev->dev, res);
> @@ -1666,6 +1688,11 @@ static int m_can_plat_probe(struct platform_device *pdev)
>  	clk_disable_unprepare(cclk);
>  disable_hclk_ret:
>  	clk_disable_unprepare(hclk);
> +pm_runtime_put:
> +	pm_runtime_put_sync(&pdev->dev);
> +pm_runtime_fail:
> +	if (ret)
> +		pm_runtime_disable(&pdev->dev);
>  failed_ret:
>  	return ret;
>  }
> @@ -1723,6 +1750,9 @@ static int m_can_plat_remove(struct platform_device *pdev)
>  	struct net_device *dev = platform_get_drvdata(pdev);
>  
>  	unregister_m_can_dev(dev);
> +
> +	pm_runtime_disable(&pdev->dev);
> +
>  	platform_set_drvdata(pdev, NULL);
>  
>  	free_m_can_dev(dev);
> 

regards,
Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |



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