RE: [PATCH v2 2/2] net: ethernet: Add driver for Sunplus SP7021

Hi Andrew,

I read specification of ICPlus IP101G (10M/100M PHY).
Bits of register 0 (control) and register 1 (status) 
are R/W or RO type. They will not be cleared after 
read. No matter how many times they are read, the 
read-back value is the same.

For example,
Value of register 0 (control) is 0x3100
Value of register 1 (status) is 0x786d 

The read-back values are always the same unless you 
unplug the cable.

Besides, we use polling mode (phydev->irq = PHY_POLL) 
PHY state-machine is triggered by using 1-Hz work-
queue, not interrupt.

We didn't find any problem after many tests after 
using 'force' mode.

Can we go with this approach?


Best regards,
Wells

quoted

Hi Andrew,


From data provided by ASIC engineer, MAC of SP7021 only reads the 4
registers of PHY:
0: Control register
1: Status register

This is the register which has latching of the link status. genphy_update_link() expects
this latching behaviour, and if the hardware reads the register, that behaviour is not
going to happen.

	Andrew