The SyncE API considerations starts ~54:00, but basically we need API for:
- Controlling the lane to pin mapping for clock recovery
- Check the EEC/DPLL state and see what's the source of reference
frequency
(in more advanced deployments)
- control additional input and output pins (GNSS input, external inputs,
recovered
frequency reference)
Now that you have pointed to a datasheet...
- Controlling the lane to pin mapping for clock recovery
So this is a PHY property. That could be Linux driving the PHY, via phylib, drivers/net/phy, or there could be firmware in the MAC driver which hides the PHY and gives you some sort of API to access it.
Check the EEC/DPLL state and see what's the source of reference frequency
Where is the EEC/DPLL implemented? Is it typically also in the PHY? Or some other hardware block?
I just want to make sure we have an API which we can easily delegate to different subsystems, some of it in the PHY driver, maybe some of it somewhere else.
Also, looking at the Marvell datasheet, it appears these registers are in the MDIO_MMD_VEND2 range. Has any of this been specified? Can we expect to be able to write a generic implementation sometime in the future which PHY drivers can share?
I just looked at a 1G Marvell PHY. It uses RGMII or SGMII towards the host. But there is no indication you can take the clock from the SGMII SERDES, it is only the recovered clock from the line. And the recovered clock always goes out the CLK125 pin, which can either be 125MHz or 25MHz.
So in this case, you have no need to control the lane to pin mapping, it is fixed, but do we want to be able to control the divider?
Do we need a mechanism to actually enumerate what the hardware can do?
Since we are talking about clocks and dividers, and multiplexors, should all this be using the common clock framework, which already supports most of this? Do we actually need something new?
Andrew