Re: [PATCH v2 1/4] serial: 8250_dw: Keep the BUSY-safe divisor hook when DLF is present

[Vinicius Pedrosa]

Hi Andy,

On Wed, 21 Oct 2026, Andy Shevchenko wrote:

> Ah, dw8250_idle_*() are already BUSY-functionality aware. So, what we need
> is to provide dw8250_idlej_*() callbacks via struct dw8250_port_data and
> make current 8250_dw::dw8250_set_divisor() to be part of dwlib.
>
> Patch 1 (dwlib): Add callback definitions for dw8250_idle_*() to struct dw8250_port_data
> Patch 2 (dw): Assign new callbacks and use them in dw8250_set_divisor()
> Patch 3 (lpss): Introduce stubs and assign new callbacks to them
> Patch 4 (dwlib): Use dw8250_idle_*() in dw8250_set_divisor()
> Patch 5 (dw): Kill now duplicate code pieces
>
> Would it work?

Yes, I think the approach works. Two details from checking the call
paths.

dw8250_setup_port() is skipped for Octeon (skip_autocfg), so 8250_dw
would still have to install the setter from probe.

For LPSS, I wonder if the idle callbacks could simply be optional.
8250_dw would provide them and LPSS could leave them NULL, avoiding
stubs and a separate LPSS patch. The common setter in dwlib would use
them when present.

I'd still prefer to keep patch 1 as the small fix with the stable tag
and do the refactoring as a separate follow-up series. Would that work
for you?

I don't have LPSS hardware, but I can build-test the LPSS side.

Thanks,
Vinicius