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From:   Arnd Bergmann <arnd@kernel.org>
Date:   Sun, 7 Mar 2021 17:01:55 +0100
Message-ID: <CAK8P3a0o4NHjXZ+ePj_Xpcw6ZmonoiR1dfkcsv=3i1JBEF4arA@mail.gmail.com>
Subject: Re: [RFT PATCH v3 21/27] tty: serial: samsung_tty: IRQ rework
To:     Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc:     Hector Martin <marcan@marcan.st>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
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On Sun, Mar 7, 2021 at 12:34 PM Krzysztof Kozlowski
<krzysztof.kozlowski@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