aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/mach-ixp4xx/Kconfig
diff options
context:
space:
mode:
authorKrzysztof Hałasa <khc@pm.waw.pl>2009-11-15 12:02:10 -0500
committerKrzysztof Hałasa <khc@pm.waw.pl>2009-12-05 10:58:39 -0500
commited5b9fa0d1c5ad1e01ff56b9acd3ff52bc783f66 (patch)
treed3068a6963c1e15d039323462a399175942fc08c /arch/arm/mach-ixp4xx/Kconfig
parentcba362221b12b102dff1f21b291fdc7b93e24a18 (diff)
IXP4xx: Extend PCI MMIO indirect address space to 1 GB.
IXP4xx CPUs can indirectly access the whole 4 GB PCI MMIO address space (using the non-prefetch registers). Previously the available space depended on the CPU variant, since one of the IXP43x platforms needed more than the usual 128 MB. 1 GB should be enough for everyone, and if not, we can trivially increase it. Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>
Diffstat (limited to 'arch/arm/mach-ixp4xx/Kconfig')
-rw-r--r--arch/arm/mach-ixp4xx/Kconfig22
1 files changed, 11 insertions, 11 deletions
diff --git a/arch/arm/mach-ixp4xx/Kconfig b/arch/arm/mach-ixp4xx/Kconfig
index 264f4d59f898..9e5070da17ae 100644
--- a/arch/arm/mach-ixp4xx/Kconfig
+++ b/arch/arm/mach-ixp4xx/Kconfig
@@ -179,21 +179,21 @@ config IXP4XX_INDIRECT_PCI
179 help 179 help
180 IXP4xx provides two methods of accessing PCI memory space: 180 IXP4xx provides two methods of accessing PCI memory space:
181 181
182 1) A direct mapped window from 0x48000000 to 0x4bffffff (64MB). 182 1) A direct mapped window from 0x48000000 to 0x4BFFFFFF (64MB).
183 To access PCI via this space, we simply ioremap() the BAR 183 To access PCI via this space, we simply ioremap() the BAR
184 into the kernel and we can use the standard read[bwl]/write[bwl] 184 into the kernel and we can use the standard read[bwl]/write[bwl]
185 macros. This is the preferred method due to speed but it 185 macros. This is the preferred method due to speed but it
186 limits the system to just 64MB of PCI memory. This can be 186 limits the system to just 64MB of PCI memory. This can be
187 problematic if using video cards and other memory-heavy devices. 187 problematic if using video cards and other memory-heavy devices.
188 188
189 2) If > 64MB of memory space is required, the IXP4xx can be 189 2) If > 64MB of memory space is required, the IXP4xx can be
190 configured to use indirect registers to access PCI This allows 190 configured to use indirect registers to access the whole PCI
191 for up to 128MB (0x48000000 to 0x4fffffff) of memory on the bus. 191 memory space. This currently allows for up to 1 GB (0x10000000
192 The disadvantage of this is that every PCI access requires 192 to 0x4FFFFFFF) of memory on the bus. The disadvantage of this
193 three local register accesses plus a spinlock, but in some 193 is that every PCI access requires three local register accesses
194 cases the performance hit is acceptable. In addition, you cannot 194 plus a spinlock, but in some cases the performance hit is
195 mmap() PCI devices in this case due to the indirect nature 195 acceptable. In addition, you cannot mmap() PCI devices in this
196 of the PCI window. 196 case due to the indirect nature of the PCI window.
197 197
198 By default, the direct method is used. Choose this option if you 198 By default, the direct method is used. Choose this option if you
199 need to use the indirect method instead. If you don't know 199 need to use the indirect method instead. If you don't know