RE: [EXT] Re: [PATCH net-next 10/13] net: mvpp2: reset the XPCS while reconfiguring the serdes lanes

[Stefan Chulski]

> -----Original Message-----
> From: Antoine Tenart <antoine.tenart@xxxxxxxxxxx>
> Sent: Monday, February 18, 2019 12:52 PM
> To: Russell King - ARM Linux admin <linux@xxxxxxxxxxxxxxx>
> Cc: Antoine Tenart <antoine.tenart@xxxxxxxxxxx>; davem@xxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> thomas.petazzoni@xxxxxxxxxxx; maxime.chevallier@xxxxxxxxxxx;
> gregory.clement@xxxxxxxxxxx; miquel.raynal@xxxxxxxxxxx; Nadav Haklai
> <nadavh@xxxxxxxxxxx>; Stefan Chulski <stefanc@xxxxxxxxxxx>; Yan
> Markman <ymarkman@xxxxxxxxxxx>; mw@xxxxxxxxxxxx
> Subject: [EXT] Re: [PATCH net-next 10/13] net: mvpp2: reset the XPCS while
> reconfiguring the serdes lanes
> 
> External Email
> 
> ----------------------------------------------------------------------
> Russell,
> 
> On Mon, Feb 18, 2019 at 10:47:57AM +0000, Russell King - ARM Linux admin
> wrote:
> >
> > Another case that needs to be considered: if the XPCS should be placed
> > into reset while reconfiguring the serdes lanes, is the same treatment
> > needed for the GMAC?
> 
> That's something I wanted to check as well. I don't know for the GMAC, while
> I'm sure the documentation explicitly state to put the XPCS in reset when
> reconfiguring the lanes.

HW recommendation upon Serdes reconfiguration are the following:

1. Disable port(CTRL0_REG - in XLG/GMAC) 
2. Put port in reset (both XLG/GMAC)
3. For KR - put in reset MPCS (MAC control clock, RX SD clock, TX SD clock), XPSC is RXAUI/XAUI clock domain
4. Power down Serdes lane

Do reconfiguration of Serdes.

5. Enable Serdes lane
6. Disable MPCS reset for KR
7. Disable port reset (both XLG/GMAC)
8. Enable port  (both XLG/GMAC)

Stefan,
Best Regards.