On 17/06/2022 13:32, Sean Anderson wrote: > At the moment, MEMACs are configured almost completely based on the > phy-connection-type. That is, if the phy interface is RGMII, it assumed > that RGMII is supported. For some interfaces, it is assumed that the > RCW/bootloader has set up the SerDes properly. The actual link state is > never reported. > > To address these shortcomings, the driver will need additional > information. First, it needs to know how to access the PCS/PMAs (in > order to configure them and get the link status). The SGMII PCS/PMA is > the only currently-described PCS/PMA. Add the XFI and QSGMII PCS/PMAs as > well. The XFI (and 1GBase-KR) PCS/PMA is a c45 "phy" which sits on the > same MDIO bus as SGMII PCS/PMA. By default they will have conflicting > addresses, but they are also not enabled at the same time by default. > Therefore, we can let the default address for the XFI PCS/PMA be the > same as for SGMII. This will allow for backwards-compatibility. > > QSGMII, however, cannot work with the current binding. This is because > the QSGMII PCS/PMAs are only present on one MAC's MDIO bus. At the > moment this is worked around by having every MAC write to the PCS/PMA > addresses (without checking if they are present). This only works if > each MAC has the same configuration, and only if we don't need to know > the status. Because the QSGMII PCS/PMA will typically be located on a > different MDIO bus than the MAC's SGMII PCS/PMA, there is no fallback > for the QSGMII PCS/PMA. > > MEMACs (across all SoCs) support the following protocols: > > - MII > - RGMII > - SGMII, 1000Base-X, and 1000Base-KX > - 2500Base-X (aka 2.5G SGMII) > - QSGMII > - 10GBase-R (aka XFI) and 10GBase-KR > - XAUI and HiGig > > Each line documents a set of orthogonal protocols (e.g. XAUI is > supported if and only if HiGig is supported). Additionally, > > - XAUI implies support for 10GBase-R > - 10GBase-R is supported if and only if RGMII is not supported > - 2500Base-X implies support for 1000Base-X > - MII implies support for RGMII > > To switch between different protocols, we must reconfigure the SerDes. > This is done by using the standard phys property. We can also use it to > validate whether different protocols are supported (e.g. using > phy_validate). This will work for serial protocols, but not RGMII or > MII. Additionally, we still need to be compatible when there is no > SerDes. > > While we can detect 10G support by examining the port speed (as set by > fsl,fman-10g-port), we cannot determine support for any of the other > protocols based on the existing binding. In fact, the binding works > against us in some respects, because pcsphy-handle is required even if > there is no possible PCS/PMA for that MAC. To allow for backwards- > compatibility, we use a boolean-style property for RGMII (instead of > presence/absence-style). When the property for RGMII is missing, we will > assume that it is supported. The exception is MII, since no existing > device trees use it (as far as I could tell). > > Unfortunately, QSGMII support will be broken for old device trees. There > is nothing we can do about this because of the PCS/PMA situation (as > described above). > > Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx> Thanks for the patch but you add too many new properties. The file should be converted to YAML/DT schema first. Best regards, Krzysztof
