Subject: [PATCH 13/15] ARM: make mach/io.h include optional

From: [email-masked] (Arnd Bergmann)
Date: Tue, 14 Feb 2012 01:06:32 +0000

On Monday 13 February 2012, H Hartley Sweeten wrote:
> > +#ifdef CONFIG_NEED_MACH_IO_H
> >  #include <mach/io.h>
> > +#else
> > +#define __io(a)              ({ (void)(a); __typesafe_io(0); })
> > +#define __mem_pci(a) (a)
> > +#endif
> 
> Rob,
> 
> I compile and boot tested these patches on EP93xxbut did not check them
> with sparse.
> 
> Most of the mach/io.h headers you remove in Patch 14/15 have the __io
> macro defined like:
> 
> #define __io(a)         __typesafe_io(a)
> 
> Does your change above still keep the __io macro typesafe?
> 
> They don't appear equivalent to me...

It's not equivalent, but the new version is more correct for most
platforms because it turns a random pointer dereference into a NULL
pointer dereference.

If you have none of PCI/ISA/PCMCIA, then inb/outb should never be
used. Ideally we would undefine __io in that case, which results
in the inb/outb stuff also not getting defined, but some drivers
like 8250 serial then fail to build even for systems that only
use the readl/writel path.

	Arnd