linux/drivers/video/omap2
Tomi Valkeinen 4422c04bbb 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>
2010-12-15 11:16:08 +02:00
..
displays OMAP: DSS2: don't power off a panel twice 2010-10-22 23:21:14 +03:00
dss OMAP: DSS2: DSI: Remove extra iounmap in error path 2010-10-22 23:21:05 +03:00
omapfb OMAP: DSS2: OMAPFB: Allow usage of def_vrfb only for omap2,3 2010-10-22 23:21:07 +03:00
Kconfig OMAP: DSS2: Add generic and Sharp panel drivers 2009-12-09 18:19:42 +02:00
Makefile OMAP: DSS2: Add generic and Sharp panel drivers 2009-12-09 18:19:42 +02:00
vram.c OMAP: DSS: VRAM: Align start & size of vram to 2M 2010-12-15 11:16:08 +02:00
vrfb.c OMAP: Add support for VRFB rotation engine 2009-12-09 12:04:33 +02:00