Re: [RESEND PATCH v2 9/9] ath5k: Constify ioreadX() iomem argument (as in generic implementation)

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Rich Felker <dalias@libc.org>, Jiri Slaby <jirislaby@gmail.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
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Subject: Re: [RESEND PATCH v2 9/9] ath5k: Constify ioreadX() iomem argument (as in generic implementation)
Date: Mon, 24 Feb 2020 13:54:00 +0100	[thread overview]
Message-ID: <CAMuHMdVev0PLF=8bD3nHrhcU9UgM-DAgdQpXi09PgvAxdbt24A@mail.gmail.com> (raw)
In-Reply-To: <20200224124744.GA1949@pi3>

Hi Krzysztof,

On Mon, Feb 24, 2020 at 1:47 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> On Thu, Feb 20, 2020 at 10:48:33AM +0100, Jiri Slaby wrote:
> > On 19. 02. 20, 18:50, Krzysztof Kozlowski wrote:
> > > The ioreadX() helpers have inconsistent interface.  On some architectures
> > > void *__iomem address argument is a pointer to const, on some not.
> > >
> > > Implementations of ioreadX() do not modify the memory under the address
> > > so they can be converted to a "const" version for const-safety and
> > > consistency among architectures.
> > >
> > > Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
> > > Acked-by: Kalle Valo <kvalo@codeaurora.org>
> > > ---
> > >  drivers/net/wireless/ath/ath5k/ahb.c | 10 +++++-----
> > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/net/wireless/ath/ath5k/ahb.c b/drivers/net/wireless/ath/ath5k/ahb.c
> > > index 2c9cec8b53d9..8bd01df369fb 100644
> > > --- a/drivers/net/wireless/ath/ath5k/ahb.c
> > > +++ b/drivers/net/wireless/ath/ath5k/ahb.c
> > > @@ -138,18 +138,18 @@ static int ath_ahb_probe(struct platform_device *pdev)
> > >
> > >     if (bcfg->devid >= AR5K_SREV_AR2315_R6) {
> > >             /* Enable WMAC AHB arbitration */
> > > -           reg = ioread32((void __iomem *) AR5K_AR2315_AHB_ARB_CTL);
> > > +           reg = ioread32((const void __iomem *) AR5K_AR2315_AHB_ARB_CTL);
> >
> > While I understand why the parameter of ioread32 should be const, I
> > don't see a reason for these casts on the users' side. What does it
> > bring except longer code to read?
>
> Because the argument is an int:
>
> drivers/net/wireless/ath/ath5k/ahb.c: In function ‘ath_ahb_probe’:
> drivers/net/wireless/ath/ath5k/ahb.c:141:18: warning: passing argument 1 of ‘ioread32’ makes pointer from integer without a cast [-Wint-conversion]
>    reg = ioread32(AR5K_AR2315_AHB_ARB_CTL);

That's an argument for keeping the cast to "void __iomem *", not for
adding the "const", right?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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