[PATCH] PCI: generic: map config window in one go

[Will Deacon]

Hi Ard,

On Fri, Jan 29, 2016 at 03:17:15PM +0100, Ard Biesheuvel wrote:
> Instead of iterating over the PCI config window and performing individual
> ioremap() calls on all the adjacent slices, perform a single ioremap() to
> map the entire region, and divvy it up later. This not only prevents
> leaving some of it mapped if we fail half way through, it also ensures that
> archs that support huge-vmap can use section mappings to perform the
> mapping.
> 
> On my Seattle A0 box, this transforms 128 separate 1 MB mappings that are
> mapped down to 4 KB pages into a single 128 MB mapping using 2 MB sections,
> saving 512 KB worth of page tables.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---

The code was written this way in response to feedback during driver review
that we couldn't necessarily grab that much contiguous vmalloc space on
32-bit ARM. Unless that's changed, we probably want to to predicate this
change on having a 64-bit arch.

Will