Messages in this thread | | | Date | Sat, 23 Sep 2023 20:51:44 +0300 | Subject | Re: [PATCH net-next v2 00/10] define and enforce phylink bindings | From | Arınç ÜNAL <> |
| |
On 23.09.2023 18:12, Andrew Lunn wrote: > On Sat, Sep 23, 2023 at 09:28:41AM +0300, Arınç ÜNAL wrote: >> On 23.09.2023 01:36, Andrew Lunn wrote: >>> You are missing: >>> >>> - The MAC has firmware driving the PHY, nothing for linux to do. >>> >>> There are properties in ethernet-controller.yaml the MAC driver would >>> however like to use such as local-mac-address, max-frame-size, >>> nvmem-cell-names etc. >> >> This is interesting. This is clearly a hardware difference of the ethernet >> controller. >> >> I believe this fits case 1. There's still an MDIO bus the ethernet >> controller uses, there's still a PHY on the MDIO bus which the ethernet >> controller uses. > > Why must there be an MDIO bus? All the bus provides is a communication > channel to the PHY. There are PHYs which are memory mapped, or use > I2C. SFP are a good example of I2C, which Linux maps to MDIO just to > make things simple, but the hardware is I2C. Why must there be a PHY? > Maybe it is a Base-K link, i.e. a baseboard link to a switch, or a BMC > or something.
There's no requirement for an MDIO bus or a PHY. If the MAC is connected to a PHY, only the PHY node needs to be described. The PHY can be controlled by any interface, I2C, MDIO, or something else. If there's no PHY, the fixed-link property would be used to describe the link.
> >> The only difference is the firmware of the ethernet >> controller controls... What exactly does the firmware control that a Linux >> driver would have controlled instead? Just configuring the link settings of >> the MAC? > > A MAC driver implements struct ethtool_ops:::get_link_settings and > set_link_settings. For a MAC driver using phylib or phylink they > typically then call into phylib or phylink to do the actual work, > maybe with a bit of pre-processing in the MAC driver. > > A MAC driver using firmware would typically make an RPC into the > firmware to implement these calls. > > There is a MAC driver currently under review which does not have a PHY > at all. The MAC is directly connected to a switch, all within one > IC. The link is always running at 5Gbps, the link is always up. It is > physically impossible to connect a PHY, so get_link_settings just > returns hard coded values.
The fixed-link property would be used to describe the link of the MAC here.
Arınç
| |