Re: [PATCH v2] net: mtk_sgmii: implement mtk_pcs_ops

"Russell King (Oracle)" [off-list ref] writes:

On Mon, Jan 16, 2023 at 07:30:27PM +0100, Bjørn Mork wrote:

quoted

"Russell King (Oracle)" [off-list ref] writes:

quoted

That all looks fine. However, I'm running out of ideas.

Thanks a lot for the effort in any case.  It's comforting that even the
top experts can't figure out this one :-)

quoted

What we seem to have is:

PHY:
VSPEC1_SGMII_CTRL = 0x34da
VSPEC1_SGMII_STAT = 0x000e

The PHY is programmed to exchange SGMII with the host PCS, and it
says that it hasn't completed that exchange (bit 5 of STAT).

The Mediatek PCS says:
BMCR = 0x1140		AN enabled
BMSR = 0x0008		AN capable
ADVERTISE = 0x0001	SGMII response (bit 14 is clear, hardware is
			supposed to manage that bit)
LPA = 0x0000		SGMII received control word (nothing)
SGMII_MODE = 0x011b	SGMII mode, duplex AN, 1000M, Full duplex,
			Remote fault disable

which all looks like it should work - but it isn't.

One last thing I can think of trying at the moment would be writing
the VSPEC1_SGMII_CTRL with 0x36da, setting bit 9 which allegedly
restarts the SGMII exchange. There's some comments in the PHY driver
that this may be needed - maybe it's necessary once the MAC's PCS
has been switched to SGMII mode.

Tried that now.  Didn't change anything.  And still no packets.

root@OpenWrt:/# mdio mdio-bus 6:30 raw 8
0x34da
root@OpenWrt:/# mdio mdio-bus 6:30 raw 9
0x000e
root@OpenWrt:/# mdio mdio-bus 6:30 raw 8 0x36da
root@OpenWrt:/# mdio mdio-bus 6:30 raw 8
0x34da
root@OpenWrt:/# mdio mdio-bus 6:30 raw 9
0x000e

If bit 9 is indeed the restart-an bit, it will be self-clearing, so
I wouldn't expect a read back of it to change to 0x36da.

I guess next thing to try is clearing and setting the AN enable bit,
bit 12, so please try this:

mdio mdio-bus 6:30 raw 8 0x24da
mdio mdio-bus 6:30 raw 8 0x36da
mdio mdio-bus 6:30 raw 9

If that doesn't work, then let's try something a bit harder:

mdio mdio-bus 6:30 raw 8 0xb4da
mdio mdio-bus 6:30 raw 9

Please let me know the results from those.

OK, back to the original dts with phy-mode = "2500base-x", with peer set
to 1G.  Still no success:

root@OpenWrt:/# mdio mdio-bus 6:30 raw 8
0x34da
root@OpenWrt:/# mdio mdio-bus 6:30 raw 9
0x000e
root@OpenWrt:/#  mdio mdio-bus 6:30 raw 8 0x24da
root@OpenWrt:/# mdio mdio-bus 6:30 raw 8 0x36da
root@OpenWrt:/# mdio mdio-bus 6:30 raw 9
0x000e
root@OpenWrt:/# mdio mdio-bus 6:30 raw 8 0xb4da
root@OpenWrt:/# mdio mdio-bus 6:30 raw 9
0x000e



Bjørn