Messages in this thread | | | Subject | Re: (EXT) Re: [PATCH net-next 1/4] net: dsa: allow switch drivers to override default slave PHY addresses | From | Matthias Schiffer <> | Date | Tue, 31 Mar 2020 11:09:32 +0200 |
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On Mon, 2020-03-30 at 20:04 -0700, Florian Fainelli wrote: > > On 3/30/2020 6:53 AM, Matthias Schiffer wrote: > > Avoid having to define a PHY for every physical port when PHY > > addresses > > are fixed, but port index != PHY address. > > > > Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com > > > > > You could do this much more elegantly by doing this with Device Tree > and > specifying the built-in PHYs to be hanging off the switch's internal > MDIO bus and specifying the port to PHY address mapping, you would > only > patch #4 then.
This does work indeed, but it seems we have different ideas on elegance.
I'm not happy about the fact that an implementor needs to study the switch manual in great detail to find out about things like the PHY address offsets when the driver could just to the right thing by default. Requiring this only for some switch configurations, while others work fine with the defaults, doesn't make this any less confusing (I'd even argue that it would be better if there weren't any default PHY and IRQ mappings for the switch ports, but I also understand that this can't easily be removed at this point...)
In particular when PHY IRQ support is desired (not implemented on the PHY driver side for this switch yet; not sure if my current project will require it), indices are easy to get wrong - which might not be noticed as long as there is no PHY driver with IRQ support for the port PHYs, potentially breaking existing Device Trees with future kernel updates. For this reason, I think at least patch #2 should be considered even if #1 and #3 are rejected.
Kind regards, Matthias
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