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authorTomi Valkeinen <tomi.valkeinen@nokia.com>2010-12-14 14:16:59 +0200
committerTomi Valkeinen <tomi.valkeinen@nokia.com>2010-12-15 11:16:08 +0200
commit4422c04bbb09f1864e2ce27296457f86d4167fe2 (patch)
tree43df9d94a388b61174ff99b3e768ed4ce3020cd0 /drivers
parentcf7d7e5a1980d1116ee152d25dac382b112b9c17 (diff)
OMAP: DSS: VRAM: Align start & size of vram to 2M
Align the start address and size of VRAM area to 2M as per comments from Russell King: > > So, why SZ_2M? > > Firstly, that's the granularity which we allocate page tables - one > Linux page table covers 2MB of memory. We want to avoid creating page > tables for the main memory mapping as that increases TLB pressure through > the use of additional TLB entries, and more page table walks. > > Plus, we never used to allow the kernel's direct memory mapping to be > mapped at anything less than section size - this restriction has since > been lifted due to OMAP SRAM problems, but I'd rather we stuck with it > to ensure that we have proper behaviour from all parts of the system. > > Secondly, we don't want to end up with lots of fragmentation at the end > of the memory mapping as that'll reduce performance, not only by making > the pfn_valid() search more expensive. > > Emsuring a minimum allocation size and alignment makes sure that the > regions can be coalesced together into one block, and minimises run-time > expenses. > > So please, 2MB, or if you object, at the _very_ _least_ 1MB. But > definitely not PAGE_SIZE. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com> Acked-by: Tony Lindgren <tony@atomide.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/video/omap2/vram.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/video/omap2/vram.c b/drivers/video/omap2/vram.c
index 2fd7e5271be..9441e2eb3de 100644
--- a/drivers/video/omap2/vram.c
+++ b/drivers/video/omap2/vram.c
@@ -551,7 +551,7 @@ void __init omap_vram_reserve_sdram_memblock(void)
if (!size)
return;
- size = PAGE_ALIGN(size);
+ size = ALIGN(size, SZ_2M);
if (paddr) {
if (paddr & ~PAGE_MASK) {
@@ -576,7 +576,7 @@ void __init omap_vram_reserve_sdram_memblock(void)
return;
}
} else {
- paddr = memblock_alloc(size, PAGE_SIZE);
+ paddr = memblock_alloc(size, SZ_2M);
}
memblock_free(paddr, size);