From: Pawel Chmielewski <redacted>
Date: Wed, 23 Aug 2023 19:56:24 +0200

On Sun, Aug 20, 2023 at 12:20:43PM -0700, Greenwalt, Paul wrote:

quoted

On 8/20/2023 11:54 AM, Andrew Lunn wrote:

quoted

On Sat, Aug 19, 2023 at 02:39:41AM -0700, Paul Greenwalt wrote:

quoted

The need to map Ethtool forced speeds to  Ethtool supported link modes is
common among drivers. To support this move the supported link modes maps
implementation from the qede driver. This is an efficient solution
introduced in commit 1d4e4ecccb11 ("qede: populate supported link modes
maps on module init") for qede driver.

ethtool_forced_speed_maps_init() should be called during driver init
with an array of struct ethtool_forced_speed_map to populate the
mapping. The macro ETHTOOL_FORCED_SPEED_MAP is a helper to initialized
the struct ethtool_forced_speed_map.

Is there any way to reuse this table:

https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/phy-core.c#L161

Seems silly to have multiple tables if this one can be made to work.
It is also used a lot more than anything you will add, which has just
two users so far, so problems with it a likely to be noticed faster.

	Andrew

Yes, we'll can look into that.

BTW,

drivers/net/ethernet/qlogic/qed/qed_main.c
drivers/net/pcs/pcs-xpcs.c

also have similar stuff and could probably make use of the generic stuff
you're doing as well (qed_main was also done by me).
Not speaking of

drivers/net/phy/phylink.c

We probably should unify all that...

Let me think how we could do that.
Andrew's idea is good. But most high-speed NICs, which have a standalone
management firmware for PHY, don't use phylib/phylink.
So in order to be able to unify all that, they should have ->supported
bitmap somewhere else. Not sure struct net_device is the best place...

If I recall Phylink logics correctly (it's been a while since I last
time was working with my embedded project),

1) in the NIC (MAC) driver, you initialize ->supported with *speeds* and
   stuff like duplex, no link modes;
2) Phylink core sets the corresponding link mode bits;
3) phylib core then clears the bits unsupported by the PHY IIRC

The third step in case with those NICs with FW-managed PHYs should be
done manually in the MAC driver somewhere. Like "I am qede and I don't
support mode XX at 50Gbps, but support the rest, so I clear that one bit".
Then the networking core should be able to play this association game
itself. That would remove a good amount of boilerplating.

I think it would be better to leave the maps in the code of respective drivers, as they are too much hardware related. 
Even for a single speed, the sets of supported link modes may vary between the devices.
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Thanks,
Olek