Re: [PATCH net-next v2 07/10] net: phy: marvell10g: Add support for 2.5GBASET

Hello Russell,

On Thu, 7 Feb 2019 23:48:24 +0000
Russell King - ARM Linux admin [off-list ref] wrote:

On Thu, Feb 07, 2019 at 10:49:36AM +0100, Maxime Chevallier wrote:

quoted

The Marvell Alaska family of PHYs supports 2.5GBaseT and 5GBaseT modes,
as defined in the 802.3bz specification.

When the link partner requests a 2.5GBASET link, the PHY will
reconfigure it's MII interface to 2500BASEX.

At 5G, the PHY will reconfigure it's interface to 5GBASE-R, but this
mode isn't supported by any MAC for now.

This was tested with :
 - The 88X3310, which is on the MacchiatoBin  

Hi Maxime,

Looking deeper at this, I think we actually need an additional patch at
the beginning of your series.

The default AN advertisement in 7.32 is 0x1181 - which includes the
2.5G and 5G modes.  We need to clear these bits, so that when the 10G
mode disabled via ethtool, we do not switch to 2.5G or 5G speed (both
of which are not currently reported as supported.)  Such a patch needs
backporting to stable kernels.

Good catch. The issue seems fixed by Andrew's patch :
3de97f3c6308 ("net: phy: marvell10g: use genphy_c45_an_config_aneg")

However, the fix should indeed be backported to the -stable trees, I've
been able to repdocude this on 4.20. I'll take care of sending a patch
to -net for that.

Thanks for reporting this,

Maxime