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SubjectRe: Complete support PC-9800 for 2.5.64-ac4 (11/11) SCSI
On 16 Mar 2003, James Bottomley wrote:
> On Sat, 2003-03-15 at 19:15, Osamu Tomita wrote:
> > /* This is what the 3393 chip looks like to us */
> > typedef struct {
> > +#ifdef CONFIG_WD33C93_PIO
> > + unsigned int SASR;
> > + unsigned int SCMD;
> > +#else
> > volatile unsigned char *SASR;
> > volatile unsigned char *SCMD;
> > +#endif
> > } wd33c93_regs;
> >
>
> This really doesn't look right. For non PIO (which is all drivers apart
> from yours), they expect to dereference SASR to get the port number (as
> an unsigned char). If you remove the dereference, don't they all break?

On m68k and MIPS, we do not derefence SASR to get the port number, SASR _is_
the MMIO pointer to the 8-bit SASR register. Hence you access the register by
dereferencing the pointer.

> Perhaps the better thing to do is to make your driver use an unsigned
> int *, so the dereference works in all cases.

Actually, it was my suggestion to remove the dereference for PIO accesses. In
that case SASR contains the I/O port register.

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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