linux-kernel - Re: [PATCH v2 09/16] reset: starfive-jh7100: Add StarFive JH7100 reset driver

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Message-ID: <CANBLGcxDUNib4C0mrP1bYnJSLyZn7rmV1wwJyj5tK4-nbMnu9g@mail.gmail.com>
Date:   Fri, 22 Oct 2021 15:50:21 +0200
From:   Emil Renner Berthing <kernel@...il.dk>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     linux-riscv <linux-riscv@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jiri Slaby <jirislaby@...nel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Sagar Kadam <sagar.kadam@...ive.com>,
        Drew Fustini <drew@...gleboard.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Michael Zhu <michael.zhu@...rfivetech.com>,
        Fu Wei <tekkamanninja@...il.com>,
        Anup Patel <anup.patel@....com>,
        Atish Patra <atish.patra@....com>,
        Matteo Croce <mcroce@...rosoft.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 09/16] reset: starfive-jh7100: Add StarFive JH7100
 reset driver

On Fri, 22 Oct 2021 at 15:39, Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> On Fri, Oct 22, 2021 at 4:35 PM Emil Renner Berthing <kernel@...il.dk> wrote:
> > On Fri, 22 Oct 2021 at 14:56, Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> > > On Thu, Oct 21, 2021 at 8:43 PM Emil Renner Berthing <kernel@...il.dk> wrote:
>
> ...
>
> > > Why all these ugly % 32 against constants?
> >
> > Because the JH7100_RST_ values goes higher than 31. There is a
> > BIT_MASK macro, but that does % BITS_PER_LONG and this is a 64bit
> > machine.
>
> And? It's exactly what you have to use!


> > > Can you convert this to simple
> > >
> > >   if (assert)
> > >     ret = readl_...
> > >   else
> > >     ret = readl_...
> > >
> > > below?
> >
> > I don't see how that would work. We're using the done value in in the
> > readl_poll_timeout. Maybe you can be a bit more explicit.
>
> Supply done either == mask or == ^mask. Try it.

So you want this?
if (assert)
  ret = readl_poll_timeout_atomic(reg_status, value, (value & mask) ==
done, 0, 1000);
else
  ret = readl_poll_timeout_atomic(reg_status, value, (value & mask) ==
^done, 0, 1000);

The compiler might be clever enough, but I'd worry the long body of
the readl_poll_timeout_atomic macro is inline twice. Rather than just
flipping the bit in `done`.