Re: [RFT PATCH v3 08/27] asm-generic/io.h: Add a non-posted variant of ioremap()

[Hector Martin]

On 25/03/2021 04.09, Arnd Bergmann wrote:
> On Wed, Mar 24, 2021 at 7:12 PM Will Deacon <will@xxxxxxxxxx> wrote:
> > > +/*
> > > + * ioremap_np needs an explicit architecture implementation, as it
> > > + * requests stronger semantics than regular ioremap(). Portable drivers
> > > + * should instead use one of the higher-level abstractions, like
> > > + * devm_ioremap_resource(), to choose the correct variant for any given
> > > + * device and bus. Portable drivers with a good reason to want non-posted
> > > + * write semantics should always provide an ioremap() fallback in case
> > > + * ioremap_np() is not available.
> > > + */
> > > +#ifndef ioremap_np
> > > +#define ioremap_np ioremap_np
> > > +static inline void __iomem *ioremap_np(phys_addr_t offset, size_t size)
> > > +{
> > > +     return NULL;
> > > +}
> > > +#endif
> >
> > Can we implement the generic pci_remap_cfgspace() in terms of ioremap_np()
> > if it is supported by the architecture? That way, we could avoid defining
> > both on arm64.
>
> Good idea. It needs a fallback in case the ioremap_np() fails on most
> architectures, but that sounds easy enough.
>
> Since pci_remap_cfgspace() only has custom implementations, it sounds like
> we can actually make the generic implementation unconditional in the end,
> but that requires adding ioremap_np() on 32-bit as well, and I would keep
> that separate from this series.

Sounds good; I'm adding a patch to adjust the generic implementation and 
remove the arm64 one in v4, and we can then complete the cleanup for 
other arches later.

--
Hector Martin (marcan@xxxxxxxxx)
Public Key: https://mrcn.st/pub