[PATCH v3 04/32] asm-generic: add ioremap_nopost() remap interface

[Lorenzo Pieralisi]

On Tue, Apr 11, 2017 at 11:39:43PM +1000, Benjamin Herrenschmidt wrote:
> On Tue, 2017-04-11 at 13:28 +0100, Lorenzo Pieralisi wrote:
> > +static inline void __iomem *ioremap_nopost(phys_addr_t offset,
> > size_t size)
> > +{
> > +       return ioremap_nocache(offset, size);
> > +}
> > +
> 
> No this is wrong as I explained.
> 
> This is a semantic that simply *cannot* be generically provided accross
> architectures as a mapping attribute.

I agree that a default implementation does not make much sense. The
only solution to this, if we want the ioremap_nopost to be made available
to generic code (and drivers - ie DT PCI host bridge drivers on ARM/ARM64
are not arch code), is to make the ioremap_nopost() call return NULL
unless overriden by arch code that can provide its semantics.

Thanks,
Lorenzo