[PATCH] netdev/fec: fix ifconfig eth0 down hang issue (v3)

[Tim Gardner]

On 04/22/2010 12:16 AM, Bryan Wu wrote:
> BugLink: http://bugs.launchpad.net/bugs/559065
>
> v3:
> if fec_enet_mii_probe() fails, we should exit the open and resume functions
> properly and give up further operations without a proper PHY connected.
>
> v2:
> Check fec_enet_mii_probe() return value directly, instead of fep->phy_dev
>
> v1:
> In ethernet connection open/close function, we need to use phy_connect
> and phy_disconnect operation before we start/stop phy. Otherwise it will
> cause system hang. Also suspend/resume needs the same fix.
>
> Signed-off-by: Bryan Wu<bryan.wu at canonical.com>
> ---
>   drivers/net/fec.c |   21 ++++++++++++++++++++-
>   1 files changed, 20 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/net/fec.c b/drivers/net/fec.c
> index 2280373..b14e4d5 100644
> --- a/drivers/net/fec.c
> +++ b/drivers/net/fec.c
> @@ -929,7 +929,13 @@ fec_enet_open(struct net_device *dev)
>   		return ret;
>
>   	/* schedule a link state check */
> +	ret = fec_enet_mii_probe(dev);
> +	if (!ret) {
> +		fec_enet_free_buffers(dev);
> +		return ret;
> +	}
>   	phy_start(fep->phy_dev);
> +
>   	netif_start_queue(dev);
>   	fep->opened = 1;
>   	return 0;
> @@ -942,10 +948,13 @@ fec_enet_close(struct net_device *dev)
>
>   	/* Don't know what to do yet. */
>   	fep->opened = 0;
> -	phy_stop(fep->phy_dev);
>   	netif_stop_queue(dev);
> +
>   	fec_stop(dev);
>
> +	if (fep->phy_dev)
> +		phy_disconnect(fep->phy_dev);
> +
>           fec_enet_free_buffers(dev);
>   	clk_disable(fep->clk);
>
> @@ -1396,6 +1405,8 @@ fec_suspend(struct platform_device *dev, pm_message_t state)
>   		fep = netdev_priv(ndev);
>   		if (netif_running(ndev)) {
>   			netif_device_detach(ndev);
> +			if (fep->phy_dev)
> +				phy_disconnect(fep->phy_dev);
>   			fec_stop(ndev);
>   			clk_disable(fep->clk);
>   		}
> @@ -1409,12 +1420,20 @@ fec_resume(struct platform_device *dev)
>   {
>   	struct net_device *ndev = platform_get_drvdata(dev);
>   	struct fec_enet_private *fep;
> +	int ret;
>
>   	if (ndev) {
>   		fep = netdev_priv(ndev);
>   		if (netif_running(ndev)) {
>   			clk_enable(fep->clk);
>   			fec_restart(ndev, 1);
> +			ret = fec_enet_mii_probe(ndev);
> +			if (!ret) {
> +				fec_stop(ndev);
> +				clk_disable(fep->clk);
> +				return ret;
> +			}
> +			phy_start(fep->phy_dev);
>   			netif_device_attach(ndev);
>   		}
>   	}

One final comment. fec_enet_mii_probe() should set fep->phy_dev=NULL 
upon entry so that if it errors out fep->phy_dev is not left with a 
bogus value (which could happen in fec_resume()).

How is the fsl-imx51 physically constructed wrt to the ethernet phy? Is 
it possible for the phy to disappear during a suspend/resume cycle?

rtg
-- 
Tim Gardner tim.gardner at canonical.com