[PATCH net v3] net: dsa: mt7530: fix impossible MDIO address and issue warning

[Florian Fainelli]

On 7/3/2024 12:44 AM, Daniel Golle wrote:
> The MDIO address of the MT7530 and MT7531 switch ICs can be configured
> using bootstrap pins. However, there are only 4 possible options for the
> switch itself: 7, 15, 23 and 31. As in MediaTek's SDK the address of the
> switch is wrongly stated in the device tree as 0 (while in reality it is
> 31), warn the user about such broken device tree and make a good guess
> what was actually intended.
> 
> This is imporant also to not break compatibility with older Device Trees
> as with commit 868ff5f4944a ("net: dsa: mt7530-mdio: read PHY address of
> switch from device tree") the address in device tree will be taken into
> account, while before it was hard-coded to 0x1f.
> 
> Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
> Signed-off-by: Daniel Golle <daniel at makrotopia.org>
> ---
> Only tested on BPi-R3 (with various deliberately broken DT) for now!

This seems like a whole lot of code just to auto-magically fix an issue 
that could be caught with a warning. I appreciate that most of these 
devices might be headless, and therefore having some attempt at getting 
functional networking goes a long way into allowing users to correct 
their mistakes.
-- 
Florian