linux-kernel - Re: [PATCH v4 3/5] net: macb: fix macb_get/set

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Date:   Wed, 13 May 2020 14:05:36 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     nicolas.ferre@...rochip.com
Cc:     linux-arm-kernel@...ts.infradead.org, netdev@...r.kernel.org,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        harini.katakam@...inx.com,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        f.fainelli@...il.com, antoine.tenart@...tlin.com,
        linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v4 3/5] net: macb: fix macb_get/set_wol() when moving to
 phylink

On Wed, May 06, 2020 at 01:37:39PM +0200, nicolas.ferre@...rochip.com wrote:
> From: Nicolas Ferre <nicolas.ferre@...rochip.com>
> 
> Keep previous function goals and integrate phylink actions to them.
> 
> phylink_ethtool_get_wol() is not enough to figure out if Ethernet driver
> supports Wake-on-Lan.
> Initialization of "supported" and "wolopts" members is done in phylink
> function, no need to keep them in calling function.
> 
> phylink_ethtool_set_wol() return value is not enough to determine
> if WoL is enabled for the calling Ethernet driver. Call it first
> but don't rely on its return value as most of simple PHY drivers
> don't implement a set_wol() function.
> 
> Fixes: 7897b071ac3b ("net: macb: convert to phylink")
> Signed-off-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
> Cc: Claudiu Beznea <claudiu.beznea@...rochip.com>
> Cc: Harini Katakam <harini.katakam@...inx.com>
> Cc: Antoine Tenart <antoine.tenart@...tlin.com>
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 53e81ab048ae..24c044dc7fa0 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -2817,21 +2817,23 @@ static void macb_get_wol(struct net_device *netdev, struct ethtool_wolinfo *wol)
>  {
>  	struct macb *bp = netdev_priv(netdev);
>  
> -	wol->supported = 0;
> -	wol->wolopts = 0;
> -
> -	if (bp->wol & MACB_WOL_HAS_MAGIC_PACKET)
> +	if (bp->wol & MACB_WOL_HAS_MAGIC_PACKET) {
>  		phylink_ethtool_get_wol(bp->phylink, wol);
> +		wol->supported |= WAKE_MAGIC;
> +
> +		if (bp->wol & MACB_WOL_ENABLED)
> +			wol->wolopts |= WAKE_MAGIC;
> +	}
>  }
>  
>  static int macb_set_wol(struct net_device *netdev, struct ethtool_wolinfo *wol)
>  {
>  	struct macb *bp = netdev_priv(netdev);
> -	int ret;
>  
> -	ret = phylink_ethtool_set_wol(bp->phylink, wol);
> -	if (!ret)
> -		return 0;
> +	/* Pass the order to phylink layer.
> +	 * Don't test return value as set_wol() is often not supported.
> +	 */
> +	phylink_ethtool_set_wol(bp->phylink, wol);

If this returns an error, does that mean WOL works or does it not?

Note that if set_wol() is not supported, this will return -EOPNOTSUPP.
What about other errors?

If you want to just ignore the case where it's not supported, then
this looks like a sledge hammer to crack a nut.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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