On Wed, Apr 07, 2021 at 02:44:39PM +0200, Andrew Lunn wrote: > > Intel mgbe is flexible to pair with any PHY. Only Aquantia/Marvell > > multi-gige PHY can do rate adaption right? > > The Marvell/Marvell multi-gige PHY can also do rate > adaptation. Marvell buying Aquantia made naming messy :-( > I should probably use part numbers. > > > Hence, we still need to take care of others PHYs. > > Yes, it just makes working around the broken design harder if you want > to get the most out of the hardware.
FYI, we really need to come up with a good solution to the rate adaption issue. What we have today really is not good. For example, take a MAC that supports only 2500base-X connected to a PHY that does rate adaption from 2500base-X to media speed. So, the PHY could be capable of 10, 100, 1G and 2.5G media speeds, and would advertise those in its supported mask. The MAC however would only report (via the validate callback) support for 2.5G speed because that's all that 2500base-X supports. What we really want when a rate adapting capable PHY is connected is to ignore what ethtool link modes the MAC supports beyond "does it support this interface type" and just use the PHY supported mask. However, that's another property of the PHY that we need to know from phylib, and it's not clear when that property should be made available. As we know from Marvell PHYs, it depends on the configurable MAC_TYPE setting, so could only be available once we've selected an interface mode for the PHY. On the other hand, we might need to know what interface mode(s) are available from the PHY and MAC to select an appropriate mode. This is not easy problems to overcome; I have had some patches for some time which allow some combination of MAC and PHY to advertise which interface mode(s) they support but I haven't been entirely happy with them to push them upstream - and it would be another phylink API change which means having to maintain the new and old code until everything has been updated (thereby making stuff a lot more complex.) After the last round of phylink API updates and the hostility from people over that, this is a big demotivating factor. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
