Re: [PATCH v1 1/2] m68k: io_mm.h - add APNE 100 MBit support

Geert Uytterhoeven
2021-06-10T07:32:31Z

Hi Finn,

On Thu, Jun 10, 2021 at 3:09 AM Finn Thain <fthain@linux-m68k.org> wrote:
> On Thu, 10 Jun 2021, Michael Schmitz wrote:
> > On 9/06/21 8:04 pm, Andreas Schwab wrote:
> > > On Jun 09 2021, Michael Schmitz wrote:
> > >
> > > > @@ -136,6 +141,9 @@ static inline u8 __iomem *isa_itb(unsigned long addr)
> > > > case ISA_TYPE_Q40: return (u8 __iomem *)Q40_ISA_IO_B(addr);
> > > > #endif
> > > > #ifdef CONFIG_AMIGA_PCMCIA
> > > > +#ifdef CONFIG_APNE100MBIT
> > > > + case ISA_TYPE_AG16: fallthrough;
> > > > +#endif
> > > > case ISA_TYPE_AG: return (u8 __iomem *)AG_ISA_IO_B(addr);
> > > Is the fallthrough annotation really needed?
> >
> > Just to shut up compiler warnings, and even that I haven't seen myself.
> >
> > I have seen a number of patches adding either comments or this annotation in
> > the core NCR5380 driver (which Finn maintains, who suggested this annotation
> > to an earlier version of the Q40/Atari io_mm.h patch), so adding annotations
> > appears to be encouraged now.
> >
> > I personally think these annotations are over the top generally, but I've
> > learned to program when computed goto statements were still en vogue.
> >
> > In this particular case, there can be no doubt that the fallthrough is
> > intentional, so on balance, I'll remove those annotations as well (unless Finn
> > strongly objects?).
> >
>
> I don't object to removing it. On the contrary, in a previous message I
> also questioned adding this particular 'fallthrough' (though I did
> recommended adding a different one).
>
> In general, there's no way to predict which static checkers are going to
> complain about any given line of code. They don't all agree about
> correctness and they are a moving target, just like fashion or reviewers'
> preferred code styles.

AFAIK, they only complain when the switch() operates on an enum,
and not all enum values are handled.

When operating on an int, there's not enough address space on
32-bit machines to handle all cases ;-)

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