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

[Vinicius Pedrosa]

Hi Andy,

On Tue, 20 Oct 2026, Andy Shevchenko wrote:

> > +		/* Keep a hook the driver has already installed */
> > +		if (!p->set_divisor)
> > +			p->set_divisor = dw8250_set_divisor;
>
> On top of my previous reply, why is this hunk needed?

dw8250_probe() installs the BUSY-safe dw8250_set_divisor() before
dw8250_setup_port() runs. Without the !p->set_divisor check, detecting
DLF replaces it with the dwlib setter, which is the BUSY problem
described in the commit message.

> In the case of existing _set_divisor, do we want to keep the possible set
> _get_divisor as well? Shouldn't we introduce a respective _get_divisor in
> 8250_dw.c?

8250_dw.c doesn't install a get_divisor, so there's no existing getter
to preserve. The dwlib getter is still needed when DLF is present,
because it computes the fractional part used by the preserved BUSY-safe
setter.

> But now I see that we have same function name in two files. Can we rename
> those in dwlib to, for example,
> dw8250_get_divisor --> dw8250_get_dfl_divisor
> dw8250_set_divisor --> dw8250_set_dfl_divisor

I'll also clean up the naming in v3: dw8250_update_dlf() with a frac
parameter, static inline after dw8250_writel_ext(), and the dwlib-local
helpers renamed to dw8250_get_dlf_divisor() and
dw8250_set_dlf_divisor().

Thanks,
Vinicius