From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Fri, 29 Jan 2016 15:52:44 +0100 Subject: [PATCH] PCI: generic: map config window in one go In-Reply-To: References: <1454077035-23872-1-git-send-email-ard.biesheuvel@linaro.org> <20160129142831.GF4541@arm.com> Message-ID: <4090946.AhejVJy7MO@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Friday 29 January 2016 15:32:01 Ard Biesheuvel wrote: > On 29 January 2016 at 15:28, Will Deacon wrote: > > 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 > >> --- > > > > 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. > > > > Ah right. How about testing for the ARCH_HAVE_HUGE_VMAP Kconfig symbol > explicitly? > Testing for 64BIT should be sufficient. Arnd