netdev - Re: Re: Re: [PATCH v2] net: mtk_sgmii: implement mtk_pcs

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Date:   Sat, 22 Oct 2022 08:25:26 +0200
From:   Frank Wunderlich <linux@...web.de>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>,
        Frank Wunderlich <frank-w@...lic-files.de>
CC:     linux-mediatek@...ts.infradead.org,
        Alexander Couzens <lynxis@...0.eu>,
        Felix Fietkau <nbd@....name>, John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Mark Lee <Mark-MC.Lee@...iatek.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: Re: Re: [PATCH v2] net: mtk_sgmii: implement mtk_pcs_ops

Am 21. Oktober 2022 23:28:09 MESZ schrieb "Russell King (Oracle)" <linux@...linux.org.uk>:
>On Fri, Oct 21, 2022 at 09:52:36PM +0200, Frank Wunderlich wrote:
>> > Gesendet: Freitag, 21. Oktober 2022 um 20:31 Uhr
>> > Von: "Russell King (Oracle)" <linux@...linux.org.uk>
>> 
>> > On Fri, Oct 21, 2022 at 07:47:47PM +0200, Frank Wunderlich wrote:
>> > > > Gesendet: Freitag, 21. Oktober 2022 um 11:06 Uhr
>> > > > Von: "Russell King (Oracle)" <linux@...linux.org.uk>
>> 
>> > > > Looking at SGMSYS_PCS_CONTROL_1, this is actually the standard BMCR in
>> > > > the low 16 bits, and BMSR in the upper 16 bits, so:
>> > > >
>> > > > At address 4, I'd expect the PHYSID.
>> > > > At address 8, I'd expect the advertisement register in the low 16 bits
>> > > > and the link partner advertisement in the upper 16 bits.
>> > > >
>> > > > Can you try an experiment, and in mtk_sgmii_init() try accessing the
>> > > > regmap at address 0, 4, and 8 and print their contents please?
>> > >
>> > > is this what you want to see?
>> 
>> > > [    1.083359] dev: 0 offset:0 0x840140
>> > > [    1.083376] dev: 0 offset:4 0x4d544950
>> > > [    1.086955] dev: 0 offset:8 0x1
>> > > [    1.090697] dev: 1 offset:0 0x81140
>> > > [    1.093866] dev: 1 offset:4 0x4d544950
>> > > [    1.097342] dev: 1 offset:8 0x1
>> >
>> > Thanks. Decoding these...
>> >
>> > dev 0:
>> >  BMCR: fixed, full duplex, 1000Mbps, !autoneg
>> >  BMSR: link up
>> >  Phy ID: 0x4d54 0x4950
>> >  Advertise: 0x0001 (which would correspond with the MAC side of SGMII)
>> >  Link partner: 0x0000 (no advertisement received, but we're not using
>> >     negotiation.)
>> >
>> > dev 1:
>> >  BMCR: autoneg (full duplex, 1000Mbps - both would be ignored)
>> >  BMSR: able to do autoneg, no link
>> >  Phy ID: 0x4d54 0x4950
>> >  Advertise: 0x0001 (same as above)
>> >  Link partner: 0x0000 (no advertisement received due to no link)
>> >
>> > Okay, what would now be interesting is to see how dev 1 behaves when
>> > it has link with a 1000base-X link partner that is advertising
>> > properly. If this changes to 0x01e0 or similar (in the high 16-bits
>> > of offset 8) then we definitely know that this is an IEEE PHY register
>> > set laid out in memory, and we can program the advertisement and read
>> > the link partner's abilities.
>> 
>> added register-read on the the new get_state function too
>> 
>> on bootup it is now a bit different
>> 
>> [    1.086283] dev: 0 offset:0 0x40140 #was previously 0x840140
>> [    1.086301] dev: 0 offset:4 0x4d544950
>> [    1.089795] dev: 0 offset:8 0x1
>> [    1.093584] dev: 1 offset:0 0x81140
>> [    1.096716] dev: 1 offset:4 0x4d544950
>> [    1.100191] dev: 1 offset:8 0x1
>> 
>> root@...-r3:~# ip link set eth1 up
>> [  172.037519] mtk_soc_eth 15100000.ethernet eth1: configuring for inband/1000base-x link mode
>> root@...-r3:~#
>> [  172.102949] offset:0 0x40140 #still same value
>
>If this is "dev: 1" the value has changed - the ANENABLE bit has been
>turned off, which means it's not going to bother receiving or sending
>the 16-bit control word. Bit 12 needs to stay set for it to perform
>the exchange.

Your right,was confused that dev 0 (fixed link to switch chip) had different value.

offset:0 0x81140 => 0x40140

So i should change offset 8 (currently 0x1) to at least 0x1 | BIT(12)? I can try to set this in the get_state callback,but i'm unsure i can read out it on my switch (basic mode changes yes,but not the value directly)...if mode is not autoneg i will see no change there.

regards Frank