netdev - Re: [PATCH] ravb: implement MTU change while device is up

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Message-ID: <20190508165015.GD24112@bigcity.dyn.berto.se>
Date:   Wed, 8 May 2019 18:50:15 +0200
From:   Niklas Söderlund 
        <niklas.soderlund@...natech.se>
To:     Ulrich Hecht <uli+renesas@...nd.eu>
Cc:     linux-renesas-soc@...r.kernel.org, netdev@...r.kernel.org,
        davem@...emloft.net, wsa@...-dreams.de, horms@...ge.net.au,
        magnus.damm@...il.com
Subject: Re: [PATCH] ravb: implement MTU change while device is up

Hi Ulrich,

Thanks for your patch.

On 2019-05-08 17:21:22 +0200, Ulrich Hecht wrote:
> Uses the same method as various other drivers: shut the device down,
> change the MTU, then bring it back up again.
> 
> Tested on Renesas D3 Draak board.
> 
> Signed-off-by: Ulrich Hecht <uli+renesas@...nd.eu>

With or without the code relayout suggested by Sergei,

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>

Also as he points out I used the same pattern for sh_eth while adding 
MTU configuration support so a similar patch there would be nice. I'm 
happy to see the fix to allow for changing the MTU when the device is up 
was so simple, yet I could not figure it out ;-) Nice work!

> ---
>  drivers/net/ethernet/renesas/ravb_main.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index ef8f089..02c247c 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1810,13 +1810,16 @@ static int ravb_do_ioctl(struct net_device *ndev, struct ifreq *req, int cmd)
>  
>  static int ravb_change_mtu(struct net_device *ndev, int new_mtu)
>  {
> -	if (netif_running(ndev))
> -		return -EBUSY;
> +	if (!netif_running(ndev)) {
> +		ndev->mtu = new_mtu;
> +		netdev_update_features(ndev);
> +		return 0;
> +	}
>  
> +	ravb_close(ndev);
>  	ndev->mtu = new_mtu;
> -	netdev_update_features(ndev);
>  
> -	return 0;
> +	return ravb_open(ndev);
>  }
>  
>  static void ravb_set_rx_csum(struct net_device *ndev, bool enable)
> -- 
> 2.7.4
> 

-- 
Regards,
Niklas Söderlund