linux-kernel - Re: [PATCH net] net: mvneta: Don't advertise 2.5G modes

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Message-ID: <20181109095715.GA30658@n2100.armlinux.org.uk>
Date:   Fri, 9 Nov 2018 09:57:15 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        thomas.petazzoni@...tlin.com, gregory.clement@...tlin.com,
        Andrew Lunn <andrew@...n.ch>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH net] net: mvneta: Don't advertise 2.5G modes

On Fri, Nov 09, 2018 at 09:17:33AM +0100, Maxime Chevallier wrote:
> Using 2.5G speed relies on the SerDes lanes being configured
> accordingly. The lanes have to be reconfigured to switch between
> 1G and 2.5G, and for now only the bootloader does this configuration.
> 
> In the case we add a Comphy driver to handle switching the lanes
> dynamically, it's better for now to stick with supporting only 1G and
> add advertisement for 2.5G once we really are capable of handling both
> speeds without problem.
> 
> Since the interface mode is initialy taken from the DT, we want to make
> sure that adding comphy support won't break boards that don't update
> their dtb.
> 
> Fixes: da58a931f248 ("net: mvneta: Add support for 2500Mbps SGMII")
> Reported-by: Andrew Lunn <andrew@...n.ch>
> Reported-by: Russell King <linux@...linux.org.uk>
> Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>

As we discussed on IRC... however, please can we wait until Monday/
Tuesday before merging this patch to allow for some further thought
and discussion - by which time I expect to have a comphy driver.

Thanks.

> ---
>  drivers/net/ethernet/marvell/mvneta.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index 5bfd349bf41a..c19ecd153499 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -3343,7 +3343,6 @@ static void mvneta_validate(struct net_device *ndev, unsigned long *supported,
>  	if (state->interface != PHY_INTERFACE_MODE_NA &&
>  	    state->interface != PHY_INTERFACE_MODE_QSGMII &&
>  	    state->interface != PHY_INTERFACE_MODE_SGMII &&
> -	    state->interface != PHY_INTERFACE_MODE_2500BASEX &&
>  	    !phy_interface_mode_is_8023z(state->interface) &&
>  	    !phy_interface_mode_is_rgmii(state->interface)) {
>  		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
> @@ -3357,14 +3356,9 @@ static void mvneta_validate(struct net_device *ndev, unsigned long *supported,
>  	/* Asymmetric pause is unsupported */
>  	phylink_set(mask, Pause);
>  
> -	/* We cannot use 1Gbps when using the 2.5G interface. */
> -	if (state->interface == PHY_INTERFACE_MODE_2500BASEX) {
> -		phylink_set(mask, 2500baseT_Full);
> -		phylink_set(mask, 2500baseX_Full);
> -	} else {
> -		phylink_set(mask, 1000baseT_Full);
> -		phylink_set(mask, 1000baseX_Full);
> -	}
> +	/* Half-duplex at speeds higher than 100Mbit is unsupported */
> +	phylink_set(mask, 1000baseT_Full);
> +	phylink_set(mask, 1000baseX_Full);
>  
>  	if (!phy_interface_mode_is_8023z(state->interface)) {
>  		/* 10M and 100M are only supported in non-802.3z mode */
> -- 
> 2.11.0
> 

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