[PATCH 1/4] net: mediatek: sgmii: fix powering up the SGMII phy

[Alexander 'lynxis' Couzens]

Hi Paolo,

> On Sun, 2022-08-21 at 00:45 +0200, Alexander Couzens wrote:
> > There are cases when the SGMII_PHYA_PWD register contains 0x9 which
> > prevents SGMII from working. The SGMII still shows link but no
> > traffic can flow. Writing 0x0 to the PHYA_PWD register fix the
> > issue. 0x0 was taken from a good working state of the SGMII
> > interface.  
> 
> do you have access to register documentation? what does 0x9 actually
> mean? is the '0' value based on just empirical evaluation?

I don't have any documentation which describes 0x9.
The datasheet [1] only contains the PHYA_PWD (0x10) bit and the initial
value is 0x10. 0x0 value is based on a register readout without the
patch from a working state.

I've tested it on mt7622 and Daniel Golle on mt7986.

[1] MT7622 Reference Manual, v1.0, 2018-12-19, 1972 pages

Best,
lynxis