linux-kernel - Re: [PATCH] io: Fix return type of _inb and

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Date:   Mon, 27 Jul 2020 10:04:49 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Stafford Horne <shorne@...il.com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Wei Xu <xuwei5@...ilicon.com>,
        John Garry <john.garry@...wei.com>,
        Linux-Arch <linux-arch@...r.kernel.org>
Subject: Re: [PATCH] io: Fix return type of _inb and _inl

On Sun, Jul 26, 2020 at 2:53 PM Stafford Horne <shorne@...il.com> wrote:
>
> On Sun, Jul 26, 2020 at 12:00:37PM +0300, Andy Shevchenko wrote:
> > On Sun, Jul 26, 2020 at 6:14 AM Stafford Horne <shorne@...il.com> wrote:
> > >
> > > The return type of functions _inb, _inw and _inl are all u16 which looks
> > > wrong.  This patch makes them u8, u16 and u32 respectively.
> > >
> > > The original commit text for these does not indicate that these should
> > > be all forced to u16.
> >
> > Is it in alight with all architectures? that support this interface natively?
> >
> > (Return value is arch-dependent AFAIU, so it might actually return
> > 16-bit for byte read, but I agree that this is weird for 32-bit value.
> > I think you have elaborate more in the commit message)
>
> Well, this is the generic io code,  at least these api's appear to not be different
> for each architecture.  The output read by the architecture dependant code i.e.
> __raw_readb() below is getting is placed into a u8.  So I think the output of
> the function will be u8.
>
> static inline u8 _inb(unsigned long addr)
> {
>         u8 val;
>
>         __io_pbr();
>         val = __raw_readb(PCI_IOBASE + addr);
>         __io_par(val);
>         return val;
> }
>
> I can expand the commit text, but I would like to get some comments from the
> original author to confirm if this is an issue.

I think your original version is fine, this was clearly just a typo and I've
applied your fix now and will forward it to Linus in the next few days,
giving John the chance to add his Ack or further comments.

Thanks a lot for spotting it and sending a fix.

      Arnd