netdev - Re: [PATCHv5 2/2] tg3: Allow ethtool to enable/disable loopback.

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Date:	Sat, 7 May 2011 09:43:21 +0200
From:	Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:	Mahesh Bandewar <maheshb@...gle.com>
Cc:	Matt Carlson <mcarlson@...adcom.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Michael Chan <mchan@...adcom.com>,
	Tom Herbert <therbert@...gle.com>
Subject: Re: [PATCHv5 2/2] tg3: Allow ethtool to enable/disable loopback.

On Fri, May 06, 2011 at 11:18:37PM -0700, Mahesh Bandewar wrote:
> This patch adds tg3_set_features() to handle loopback mode. Currently the
> capability is added for the devices which support internal MAC loopback mode.
> So when enabled, it enables internal-MAC loopback.
[...]
> diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
> index 7c7c9a8..b7270c2 100644
> --- a/drivers/net/tg3.c
> +++ b/drivers/net/tg3.c
[...]
> @@ -6319,6 +6356,24 @@ static u32 tg3_fix_features(struct net_device *dev, u32 features)
>  	return features;
>  }
>  
> +static int tg3_set_features(struct net_device *dev, u32 features)
> +{
> +	struct tg3 *tp = netdev_priv(dev);
> +	u32 changed = dev->features ^ features;
> +
> +	if (changed & NETIF_F_LOOPBACK) {
> +		if (tg3_flag(tp, LOOPBACK_ENABLED))
> +			tg3_flag_clear(tp, LOOPBACK_ENABLED);
> +		else
> +			tg3_flag_set(tp, LOOPBACK_ENABLED);
> +
> +		if (netif_running(dev))
> +			tg3_set_loopback(dev);
> +	}
> +
> +	return 0;
> +}
> +
>  static inline void tg3_set_mtu(struct net_device *dev, struct tg3 *tp,
>  			       int new_mtu)
>  {
> @@ -9485,6 +9540,13 @@ static int tg3_open(struct net_device *dev)
>  
>  	netif_tx_start_all_queues(dev);
>  
> +	/*
> +	 * Reset loopback feature if it was turned on while the device was down
> +	 * make sure that it's installed properly now.
> +	 */
> +	if (tg3_flag(tp, LOOPBACK_ENABLED))
> +		tg3_set_loopback(dev);
> +
>  	return 0;
>  
>  err_out3:
[...]

So, you've just implemented what I said about enabling loopback at the end
of tg3_open(), but you also added (redundant) flag that mirrors
dev->features & NETIF_F_LOOPBACK. Why?

Best Regards,
Michał Mirosław
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