Re: [PATCH v4 9/9] i2c: atr: add passthrough flag

Luca Ceresoli
2025-04-30T14:36:20Z

On Mon, 28 Apr 2025 13:25:14 +0300
Cosmin Tanislav <demonsingur@gmail.com> wrote:

> Some I2C ATRs can have other I2C ATRs as children. The I2C messages of
> the child ATRs need to be forwarded as-is if the parent I2C ATR can
> only do static mapping.
>
> In the case of GMSL, the deserializer I2C ATR actually doesn't have I2C
> address remapping hardware capabilities, but it is able to select which
> GMSL link to talk to, allowing it to change the address of the
> serializer.
>
> The child ATRs need to have their alias pools defined in such a way to
> prevent overlapping addresses between them, but there's no way around
> this without orchestration between multiple ATR instances.
>
> To allow for this use-case, add a flag that allows unmapped addresses
> to be passed through, since they are already remapped by the child ATRs.
>
> There's no case where an address that has not been remapped by the child
> ATR will hit the parent ATR.
>
> Signed-off-by: Cosmin Tanislav <demonsingur@gmail.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering