Re: [PATCH 2/2] serial: 8250_of: add support for an optional bus clock

Andy Shevchenko
2025-04-09T07:29:16Z

On Tue, Apr 08, 2025 at 03:11:10PM -0500, Alex Elder wrote:
> On 4/8/25 2:52 PM, Andy Shevchenko wrote:
> > On Tue, Apr 08, 2025 at 12:51:43PM -0500, Alex Elder wrote:

> > > The SpacemiT UART requires a bus clock to be enabled, in addition to
> > > it's "normal" core clock. Look up the core clock by name, and if
> > > that's found, look up the bus clock. If named clocks are used, both
> > > are required.
> > >
> > > Supplying a bus clock is optional. If no bus clock is needed, the clocks
> > > aren't named and we only look up the first clock.
> >
> > Code and description are not aligned. And What you are described above make
> > more sense to me than what's done below.
>
> I want to do this the right way.
>
> My explanation says:
> - look up the core clock by name
> - if that is found, look up the bus clock
> - both clocks are required in this case (error otherwise)
> - If the "core" clock is not found:
> - look up the first clock.
>
> And my code does:
> - look up the core clock by name (not found is OK)
> - if it is found, look up the bus clock by name
> - If that is not found or error, it's an error
> - if the "core" clock is not found
> - look up the first clock
>
> What is not aligned?

That you are telling that bus is optional and core is not, the code does the
opposite (and yes, I understand the logic behind, but why not doing the same in
the code, i.e. check for the *optional* bus clock first?

> > Also can we simply not not touch this conditional at all, but just add
> > a new one before? Like
> >
> > /* Get clk rate through clk driver if present */
> >
> > /* Try named clock first */
> > if (!port->uartclk) {
> > ...
> > }
> >
> > /* Try unnamed core clock */
> > // the below is just an existing code.
>
> That's easy enough. I think it might be a little more code
> but I have no problem with that.

I;m fine with a little more code, but it will be much cleaner in my point of
view and as a bonus the diff will be easier to review.

> > if (!port->uartclk) {
> > ...
> > }

--
With Best Regards,
Andy Shevchenko