linux-kernel - Re: [PATCH v6] can: xilinx: Convert to runtime

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Message-ID: <20151022221320.GQ5257@xsjsorenbubuntu>
Date:	Thu, 22 Oct 2015 15:13:20 -0700
From:	Sören Brinkmann <soren.brinkmann@...inx.com>
To:	Kedareswara rao Appana <appana.durga.rao@...inx.com>
CC:	<anirudh@...inx.com>, <wg@...ndegger.com>, <mkl@...gutronix.de>,
	<michal.simek@...inx.com>, <linux-can@...r.kernel.org>,
	<netdev@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	Kedareswara rao Appana <appanad@...inx.com>
Subject: Re: [PATCH v6] can: xilinx: Convert to runtime_pm

Hi Kedar,

On Thu, 2015-10-22 at 10:15AM +0530, Kedareswara rao Appana wrote:
> Instead of enabling/disabling clocks at several locations in the driver,
> Use the runtime_pm framework. This consolidates the actions for runtime PM
> In the appropriate callbacks and makes the driver more readable and mantainable.
> 
> Signed-off-by: Kedareswara rao Appana <appanad@...inx.com>
[...]
>  /**
>   * xcan_probe - Platform registration call
> @@ -1072,7 +1103,7 @@ static int xcan_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	priv = netdev_priv(ndev);
> -	priv->dev = ndev;
> +	priv->dev = &pdev->dev;
>  	priv->can.bittiming_const = &xcan_bittiming_const;
>  	priv->can.do_set_mode = xcan_do_set_mode;
>  	priv->can.do_get_berr_counter = xcan_get_berr_counter;
> @@ -1114,21 +1145,30 @@ static int xcan_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> -	ret = clk_prepare_enable(priv->can_clk);
> +	ret = clk_prepare(priv->can_clk);
>  	if (ret) {
>  		dev_err(&pdev->dev, "unable to enable device clock\n");
>  		goto err_free;
>  	}
>  
> -	ret = clk_prepare_enable(priv->bus_clk);
> +	ret = clk_prepare(priv->bus_clk);

Are these clk_prepare calls needed here? The runtime PM calls do
clk_prepare_enable and clk_disable_unprepare.

>  	if (ret) {
>  		dev_err(&pdev->dev, "unable to enable bus clock\n");
> -		goto err_unprepare_disable_dev;
> +		goto err_unprepare_dev;
>  	}
>  
>  	priv->write_reg = xcan_write_reg_le;
>  	priv->read_reg = xcan_read_reg_le;
>  
> +	pm_runtime_irq_safe(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +	ret = pm_runtime_get_sync(&pdev->dev);
> +	if (ret < 0) {
> +		netdev_err(ndev, "%s: pm_runtime_get failed(%d)\n",
> +			__func__, ret);
> +		goto err_unprepare_busclk;
> +	}
> +
>  	if (priv->read_reg(priv, XCAN_SR_OFFSET) != XCAN_SR_CONFIG_MASK) {
>  		priv->write_reg = xcan_write_reg_be;
>  		priv->read_reg = xcan_read_reg_be;
> @@ -1141,22 +1181,26 @@ static int xcan_probe(struct platform_device *pdev)
>  	ret = register_candev(ndev);
>  	if (ret) {
>  		dev_err(&pdev->dev, "fail to register failed (err=%d)\n", ret);
> -		goto err_unprepare_disable_busclk;
> +		goto err_disableclks;
>  	}
>  
>  	devm_can_led_init(ndev);
> -	clk_disable_unprepare(priv->bus_clk);
> -	clk_disable_unprepare(priv->can_clk);
> +
> +	pm_runtime_put(&pdev->dev);
> +
>  	netdev_dbg(ndev, "reg_base=0x%p irq=%d clock=%d, tx fifo depth:%d\n",
>  			priv->reg_base, ndev->irq, priv->can.clock.freq,
>  			priv->tx_max);
>  
>  	return 0;
>  
> -err_unprepare_disable_busclk:
> -	clk_disable_unprepare(priv->bus_clk);
> -err_unprepare_disable_dev:
> -	clk_disable_unprepare(priv->can_clk);
> +err_disableclks:
> +	pm_runtime_put(priv->dev);
> +err_unprepare_busclk:
> +	pm_runtime_disable(&pdev->dev);
> +	clk_unprepare(priv->bus_clk);
> +err_unprepare_dev:
> +	clk_unprepare(priv->can_clk);
>  err_free:
>  	free_candev(ndev);
>  err:
> @@ -1175,11 +1219,11 @@ static int xcan_remove(struct platform_device *pdev)
>  	struct net_device *ndev = platform_get_drvdata(pdev);
>  	struct xcan_priv *priv = netdev_priv(ndev);
>  
> -	if (set_reset_mode(ndev) < 0)
> -		netdev_err(ndev, "mode resetting failed!\n");
> -
>  	unregister_candev(ndev);
> +	pm_runtime_disable(&pdev->dev);
>  	netif_napi_del(&priv->napi);
> +	clk_unprepare(priv->bus_clk);
> +	clk_unprepare(priv->can_clk);

I think this can go away when the prepare calls in probe go away.

	Thanks,
	Sören
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