Re: [PATCH net-next 5/7] net: phy: marvell10g: Force reading of 2.5/5G PMA extended abilities

Hello Andrew,

On Sun, 20 Jan 2019 20:08:09 +0100
Andrew Lunn [off-list ref] wrote:

On Fri, Jan 18, 2019 at 04:23:50PM +0100, Maxime Chevallier wrote:

quoted

As per 802.3bz, if bit 14 of (1.11) "PMA Extended Abilities" indicates
whether or not we should read register (1.21) "2.52/5G PMA Extended
Abilities", which contains information on the support of 2.5GBASET and
5GBASET.

After testing on several variants of PHYS of this family, it appears
that bit 14 in (1.11) isn't always set when it should be.

PHYs 88X3310 (on MacchiatoBin) and 88E2010 do support 2.5G and 5GBASET,
but don't have 1.11.14 set. Their register 1.21 is filled with the
correct values, indicating 2.5G and 5G support.

PHYs 88X2110 do have their 1.11.14 bit set, as it should.  

Hi Maxime

Is there anything about this in any Errata?

I haven't seen any Errata on that unfortunately.

I also thought about reading (1.4) "PMA/PMD Speed Ability", but the
2.5G and 5G speeds are also reported as not being supported on the
88X3310.

We potentially have an issue if Marvell have any PHYs in this family
which don't support 2.5G/5G. Maybe this workaround needs to check the
IDs and only enable it on device we know are broken.

I agree with you, this might be a better way to handle that issue. For
now, I've only seen that issue on the 3310 and 2010, with PHY IDs
respectively 002b09aa and 002b09ab.

I 'll add a test for ids '002b09aX', hopefully there won't be any PHYs
with these IDs that don't support 2.5/5G.

In that case, there's no need for a separate mv2110_config_init in
patch 7.

Thanks,

Maxime.

   Andrew

-- 
Maxime Chevallier, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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