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Date: Tue, 20 Oct 2020 21:06:32 +0000 From: Chris Packham <Chris.Packham@...iedtelesis.co.nz> To: Marek Behun <marek.behun@....cz>, Russell King - ARM Linux admin <linux@...linux.org.uk> CC: Andrew Lunn <andrew@...n.ch>, "vivien.didelot@...il.com" <vivien.didelot@...il.com>, "f.fainelli@...il.com" <f.fainelli@...il.com>, "olteanv@...il.com" <olteanv@...il.com>, "davem@...emloft.net" <davem@...emloft.net>, "kuba@...nel.org" <kuba@...nel.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v3 1/3] net: dsa: mv88e6xxx: Don't force link when using in-band-status On 21/10/20 3:51 am, Marek Behun wrote: > On Tue, 20 Oct 2020 15:15:25 +0100 > Russell King - ARM Linux admin <linux@...linux.org.uk> wrote: > >> On Tue, Oct 20, 2020 at 04:05:35PM +0200, Andrew Lunn wrote: >>> On Tue, Oct 20, 2020 at 03:49:40PM +0200, Marek Behun wrote: >>>> On Tue, 20 Oct 2020 11:15:52 +0100 >>>> Russell King - ARM Linux admin <linux@...linux.org.uk> wrote: >>>> >>>>> On Tue, Oct 20, 2020 at 04:45:56PM +1300, Chris Packham wrote: >>>>>> When a port is configured with 'managed = "in-band-status"' don't force >>>>>> the link up, the switch MAC will detect the link status correctly. >>>>>> >>>>>> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz> >>>>>> Reviewed-by: Andrew Lunn <andrew@...n.ch> >>>>> I thought we had issues with the 88E6390 where the PCS does not >>>>> update the MAC with its results. Isn't this going to break the >>>>> 6390? Andrew? >>>>> >>>> Russell, I tested this patch on Turris MOX with 6390 on port 9 (cpu >>>> port) which is configured in devicetree as 2500base-x, in-band-status, >>>> and it works... >>>> >>>> Or will this break on user ports? >>> User ports is what needs testing, ideally with an SFP. >>> >>> There used to be explicit code which when the SERDES reported link up, >>> the MAC was configured in software with the correct speed etc. With >>> the move to pcs APIs, it is less obvious how this works now, does it >>> still software configure the MAC, or do we have the right magic so >>> that the hardware updates itself. >> It's still there. The speed/duplex etc are read from the serdes PHY >> via mv88e6390_serdes_pcs_get_state(). When the link comes up, we >> pass the negotiated link parameters read from there to the link_up() >> functions. For ports where mv88e6xxx_port_ppu_updates() returns false >> (no external PHY) we update the port's speed and duplex setting and >> (currently, before this patch) force the link up. >> >> That was the behaviour before I converted the code, the one that you >> referred to. I had assumed the code was correct, and _none_ of the >> speed, duplex, nor link state was propagated from the serdes PCS to >> the port on the 88E6390 - hence why the code you refer to existed. >> > Russell, you are right. > SFP on 88E6390 does not work with this patch applied. > So this patch breaks 88E6390. Thanks for testing. It sounds like maybe if I make mv88e6xxx_port_ppu_updates() return true for the 6097 in serdes mode I can avoid the forced link up without affecting the 6390.
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