[RFT PATCH v3 21/27] tty: serial: samsung_tty: IRQ rework

[Arnd Bergmann]

On Sun, Mar 7, 2021 at 12:34 PM Krzysztof Kozlowski
<krzysztof.kozlowski at canonical.com> wrote:
> On 05/03/2021 17:29, Hector Martin wrote:
> > On 06/03/2021 01.20, Andy Shevchenko wrote:
> >>> I am just splitting an
> >>> existing function into two, where one takes the lock and the other does
> >>> the work. Do you mean using a different locking function? I'm not
> >>> entirely sure what you're suggesting.
> >>
> >> Yes, as a prerequisite
> >>
> >> spin_lock_irqsave -> spin_lock().
> >
> > Krzysztof, is this something you want in this series? I was trying to
> > avoid logic changes to the non-Apple paths.
>
> I don't quite get the need for such change (the code will be still
> called in interrupt handler, right?), but assuming the "why?" is
> properly documented, it can be a separate patch here.

This is only for readability: the common rule is to not disable
interrupts when they are already disabled, so a reader might wonder
if this instance of the handler is special in some case that it might
be called with interrupts enabled.

There is also a small overhead in accessing the global irq mask
register on some architectures, but for a uart that does not make
any difference of course.

While I'm generally in favor of that kind of cleanup, I'd also
prefer to leave it out of this series -- once you get into details
like this the series gets harder to review.

        Arnd