Re: Multiple SPI MCP23S17s sharing a CS line

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Thu, Nov 28, 2019 at 10:25 AM Phil Elwell <phil@xxxxxxxxxxxxxxx> wrote:
> [Me]
> > By introducing such child nodes it gets possible to reference
> > these chips by phandle <&mcp1 ...>;
> >
> > Notice use of reg attribute to address subchip.
>
> I've not spent enough time in this area to know all of the rules and
> conventions, but it strikes me that if you treat the parent as a kind of
> bus and the "reg" properties as being the addresses (rather than
> indexes) then you no longer need the present mask.

Indeed, that would involve deprecating the present mask and
use the reg =<> property to figure out which chips are
connected instead.

Yours,
Linus Walleij