Re: [net-next 3/3] net: phy: marvell-88q2xxx: Enable auto negotiation for mv88q2110

[Stefan Eichenberger <eichest@gmail.com>]

Hi Niklas,

On Sat, Sep 14, 2024 at 04:21:36PM +0200, Niklas Söderlund wrote:
> Hello,
> 
> On 2024-09-14 16:00:01 +0200, Stefan Eichenberger wrote:
> > Hi Niklas and Andrew,
> > 
> > I was able to do a first basic test on my setup. I'm using the MV88Q2110
> > and connecting it to a Göpel media converter that I use as a reference.
> 
> Thanks for testing this work.
> 
> > However, with your patch applied, I can't get a link. When I set a fixed
> > link speed of 1GBit/s and the media converter is configured as the
> > master, I can normally do: 
> > ethtool -s end1 speed 1000 master-slave forced-slave
> > After that, the link came up. However, with the changes made, I can't do
> > this anymore. Can you reproduce this in your setup?
> 
> Without this patch I can't bring up a 1GBit/s link at all, I can only 
> setup a 100 MBit/s link with,
> 
>     ethtool -s eth1 speed 100 master-slave forced-slave
> 
> If I do the same with speed set to a 1000 I never get a link. That's why 
> autoneg is a such a boon for me, as with that I do get a 1 Gbit/s link.
> 
> As you have the MV88Q2110 datasheets, can you check the register writes 
> in mv88q2110_init_seq0 and mv88q2110_init_seq1 for sanity? Maybe 
> something is not quiet right there, I have only been able to reveres 
> engineer support for autoneg so it's quiet likely.

Unfortunately this registers are not documented in the datasheet.
However, from the software initialization guide the following values
would be correct for A1 and A2 devices (A0 does not need one write):
static const struct mmd_val mv88q2110_init_seq1[] = {
	{ MDIO_MMD_PCS, 0xffde, 0x402f },
	{ MDIO_MMD_PCS, 0xfe2a, 0x3c3d},
	{ MDIO_MMD_PCS, 0xfe34, 0x4040 },
	{ MDIO_MMD_PCS, 0xfe4b, 0x9337},
	{ MDIO_MMD_PCS, 0xfe2a, 0x3c1d },
	{ MDIO_MMD_PCS, 0xfe34, 0x0040 },
	{ MDIO_MMD_AN, 0x8032, 0x0064 },
	{ MDIO_MMD_AN, 0x8031, 0x0a01 },
	{ MDIO_MMD_AN, 0x8031, 0x0c01 },
	{ MDIO_MMD_PCS, 0xFE0F, 0x0000 },
	{ MDIO_MMD_PCS, 0x800C, 0x0000 },
	{ MDIO_MMD_PCS, 0x801D, 0x0800 },
	{ MDIO_MMD_PCS, 0xfc00, 0x01c0 },
	{ MDIO_MMD_PCS, 0xfc17, 0x0425},
	{ MDIO_MMD_PCS, 0xfc94, 0x5470},
	{ MDIO_MMD_PCS, 0xfc95, 0x0055},
	{ MDIO_MMD_PCS, 0xfc19, 0x08d8},
	{ MDIO_MMD_PCS, 0xfc1a, 0x0110},
	{ MDIO_MMD_PCS, 0xfc1b, 0x0a10},
	{ MDIO_MMD_PCS, 0xfc3a, 0x2725},
	{ MDIO_MMD_PCS, 0xfc61, 0x2627},
	{ MDIO_MMD_PCS, 0xfc3b, 0x1612},
	{ MDIO_MMD_PCS, 0xfc62, 0x1c12},
	{ MDIO_MMD_PCS, 0xfc9d, 0x6367},
	{ MDIO_MMD_PCS, 0xfc9e, 0x8060},
	{ MDIO_MMD_PCS, 0xfc00, 0x01c8},
	{ MDIO_MMD_PCS, 0x8000, 0x0000},
	{ MDIO_MMD_PCS, 0x8016, 0x0011},
	{ MDIO_MMD_PCS, 0xfda3, 0x1800}, /* According to datahsheet not for Rev A0 */
	{ MDIO_MMD_PCS, 0xfe02, 0x00c0},
	{ MDIO_MMD_PCS, 0xffdb, 0x0010},
	{ MDIO_MMD_PCS, 0xfff3, 0x0020},
	{ MDIO_MMD_PCS, 0xfe40, 0x00a6},
	{ MDIO_MMD_PCS, 0xfe60, 0x0000},
	{ MDIO_MMD_PCS, 0xfe04, 0x0008},
	{ MDIO_MMD_PCS, 0xfe2a, 0x3c3d},
	{ MDIO_MMD_PCS, 0xfe4b, 0x9334},
	{ MDIO_MMD_PCS, 0xfc10, 0xf600},
	{ MDIO_MMD_PCS, 0xfc11, 0x073d},
	{ MDIO_MMD_PCS, 0xfc12, 0x000d},
	{ MDIO_MMD_PCS, 0xfc13, 0x0010},
};

On my side, your values and the ones above are working.

By the way, do you know why you only get between 800 and 850 Mbps? On my
setup I see up to 930 Mbps in bidir mode. Just asking because maybe this
is the reason why fixed speed doesn't work in your setup (would be weird
though)?

[ ID][Role] Interval           Transfer     Bitrate         Retr
[  5][TX-C]   0.00-10.01  sec  1.09 GBytes   935 Mbits/sec    0             sender
[  5][TX-C]   0.00-10.01  sec  1.09 GBytes   932 Mbits/sec                  receiver
[  7][RX-C]   0.00-10.01  sec  1.09 GBytes   933 Mbits/sec  154             sender
[  7][RX-C]   0.00-10.01  sec  1.08 GBytes   931 Mbits/sec                  receiver

Regards,
Stefan