Commit Graph

4 Commits

Author SHA1 Message Date
Russell King
45cd5290bf ARM: add dma coherent region reporting via procfs
Add a new seqfile for reporting coherent DMA allocations.  This contains
the address range, size and the function which was used to allocate
each region, allowing these allocations to be viewed in much the same
way as /proc/vmallocinfo.

The DMA coherent region has limited space, so this allows allocation
failures to be viewed, as well as finding out how much space is being
used.

Make sure this file is only readable by root - same as vmallocinfo - to
prevent information leakage.

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-01-23 10:23:57 +00:00
Russell King
459c1517f9 ARM: DMA: top-down allocation in DMA coherent region
Achieve better usage of the DMA coherent region by doing top-down
allocation rather than bottom up.  If we ask for a 128kB allocation,
this will be aligned to 128kB and satisfied from the very bottom
address.  If we then ask for a 600kB allocation, this will be aligned
to 1MB, and we will have a 896kB hole.

Performing top-down allocation resolves this by allocating the 128kB
at the very top, and then the 600kB can come in below it without any
unnecessary wastage.

This problem was reported by Janusz Krzysztofik, who had 2 x 128kB +
1 x 640kB allocations which wouldn't fit into 1MB.

Tested-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-23 17:24:11 +00:00
Russell King
5bc23d32d8 ARM: DMA coherent allocator: align remapped addresses
The DMA coherent remap area is used to provide an uncached mapping
of memory for coherency with DMA engines.  Currently, we look for
any free hole which our allocation will fit in with page alignment.

However, this can lead to fragmentation of the area, and allows small
allocations to cross L1 entry boundaries.  This is undesirable as we
want to move towards allocating sections of memory.

Align allocations according to the size, limiting the alignment between
the page and section sizes.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-07-27 10:43:48 +01:00
Russell King
13ccf3ad99 ARM: dma-mapping: split out vmregion code from dma coherent mapping code
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Ungerer <gerg@uclinux.org>
2009-11-24 17:41:34 +00:00