linux-kernel - Re: [PATCH net-next v4 05/12] net: ethernet: oa_tc6: implement error interrupts unmasking

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Date: Fri, 24 May 2024 20:12:58 +0200
From: Ramón Nordin Rodriguez <ramon.nordin.rodriguez@...roamp.se>
To: Parthiban.Veerasooran@...rochip.com
Cc: andrew@...n.ch, Pier.Beruto@...emi.com, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	horms@...nel.org, saeedm@...dia.com, anthony.l.nguyen@...el.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	corbet@....net, linux-doc@...r.kernel.org, robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
	devicetree@...r.kernel.org, Horatiu.Vultur@...rochip.com,
	ruanjinjie@...wei.com, Steen.Hegelund@...rochip.com,
	vladimir.oltean@....com, UNGLinuxDriver@...rochip.com,
	Thorsten.Kummermehr@...rochip.com, Selvamani.Rajagopal@...emi.com,
	Nicolas.Ferre@...rochip.com, benjamin.bigler@...nformulastudent.ch
Subject: Re: [PATCH net-next v4 05/12] net: ethernet: oa_tc6: implement error
 interrupts unmasking

> >>>> Is it doing this in an endless cycle?
> >>>
> >>> Exactly, so what I'm seeing is when the driver livelocks the macphy is
> >>> periodically pulling the irq pin low, the driver clears the interrupt
> >>> and repeat.
> >> If I understand correctly, you are keep on getting interrupt without
> >> indicating anything in the footer?. Are you using LAN8650 Rev.B0 or B1?.
> >> If it is B0 then can you try with Rev.B1 once?
> >>

After a considerable ammount of headscratching it seems that disabling collision
detection on the macphy is the only way of getting it stable.
When PLCA is enabled it's expected that CD causes problems, when running
in CSMA/CD mode it was unexpected (for me at least).

Disabling collision detection was discussed here 
https://lore.kernel.org/netdev/20231127104045.96722-1-ramon.nordin.rodriguez@ferroamp.se/
in a patchset that I haven't gotten around to testing through properly
and fixing up, but now it's definetly a priority.

Rev.b0 and b1 gives similar results in this domain, though I'm getting
lower throughput and it's easier/faster to get the internal error state
on rev.b1.

When CD is disabled both chip revs seems stable in all of my testing.

> > 
> > I'll check the footer content, thanks for the tip!
> > 
> > All testing has bee done with Rev.B0, we've located a set of B1 chips.
> > So we'll get on resoldering and rerunning the test scenario.
> Thanks for the consideration. But be informed that the internal PHY 
> initial settings are updated for the Rev.B1. But the one from the 
> mainline still supports for Rev.B0. So that microchip_t1s.c to be 
> updated to support Rev.B1.

I posted a suggestion for how to bringup rev.b1
https://lore.kernel.org/netdev/20240524140706.359537-1-ramon.nordin.rodriguez@ferroamp.se/

I should have prefaced the cover letter with 'ugly hacks ahead'.

> 
> Also I am in talk with our design team that whether the updated initial 
> settings for B1 are also applicable for B0. If so, then we will have 
> only one updated initial setting which supports both B0 and B1.

Any update on this?

I will submit a new revision of the lan8670 revc + disable collision
detection pathset where CD is disabled regardless of operating mode.

R