linux-kernel - Re: [PATCH] can: Fix bug in suspend/resume

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Date:	Thu, 13 Nov 2014 11:15:53 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Kedareswara rao Appana <appana.durga.rao@...inx.com>,
	wg@...ndegger.com, michal.simek@...inx.com,
	soren.brinkmann@...inx.com, grant.likely@...aro.org,
	robh+dt@...nel.org
CC:	linux-can@...r.kernel.org, netdev@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	Kedareswara rao Appana <appanad@...inx.com>
Subject: Re: [PATCH] can: Fix bug in suspend/resume

On 11/13/2014 07:58 AM, Kedareswara rao Appana wrote:
> When accessing the priv structure use container_of instead of dev_get_drvdata.

Why?

> Enable the clocks in the suspend before accessing the registers of the CAN.
> 
> Signed-off-by: Kedareswara rao Appana <appanad@...inx.com>
> ---
>  drivers/net/can/xilinx_can.c |   20 ++++++++++++++++++--
>  1 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
> index 5e8b560..63ef645 100644
> --- a/drivers/net/can/xilinx_can.c
> +++ b/drivers/net/can/xilinx_can.c
> @@ -972,15 +972,30 @@ static const struct net_device_ops xcan_netdev_ops = {
>   */
>  static int __maybe_unused xcan_suspend(struct device *dev)
>  {
> -	struct platform_device *pdev = dev_get_drvdata(dev);
> +	struct platform_device *pdev = container_of(dev,
> +			struct platform_device, dev);
>  	struct net_device *ndev = platform_get_drvdata(pdev);
>  	struct xcan_priv *priv = netdev_priv(ndev);
> +	int ret;
>  
>  	if (netif_running(ndev)) {
>  		netif_stop_queue(ndev);
>  		netif_device_detach(ndev);
>  	}
>  
> +	ret = clk_prepare_enable(priv->can_clk);
> +	if (ret) {
> +		dev_err(dev, "unable to enable device clock\n");
> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(priv->bus_clk);
> +	if (ret) {
> +		dev_err(dev, "unable to enable bus clock\n");
> +		clk_disable_unprepare(priv->can_clk);
> +		return ret;
> +	}

Now you have clock imbalance. Per suspend/resume cycle the clocks are
enabled twice, but disabled only once.

> +
>  	priv->write_reg(priv, XCAN_MSR_OFFSET, XCAN_MSR_SLEEP_MASK);
>  	priv->can.state = CAN_STATE_SLEEPING;
>  
> @@ -999,7 +1014,8 @@ static int __maybe_unused xcan_suspend(struct device *dev)
>   */
>  static int __maybe_unused xcan_resume(struct device *dev)
>  {
> -	struct platform_device *pdev = dev_get_drvdata(dev);
> +	struct platform_device *pdev = container_of(dev,
> +			struct platform_device, dev);
>  	struct net_device *ndev = platform_get_drvdata(pdev);
>  	struct xcan_priv *priv = netdev_priv(ndev);
>  	int ret;
> 

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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