Hello!
Recent changes to ioremap and unification of vmalloc regions on ARM significantly reduces the possible size of the consistent dma region. They are significantly limited allowed dma coherent/writecombine allocations.
This experimental patchset replaces custom consistent dma regions usage in dma-mapping framework in favour of generic vmalloc areas created on demand for each coherent and writecombine allocations. The main purpose for this patchset is to remove 2MiB limit of dma coherent/writecombine allocations.
Atomic allocations are served from special pool preallocated on boot, becasue vmalloc areas cannot be reliably created in atomic context.
This patch is based on vanilla v3.4-rc7 release.
Atomic allocations have been tested with s3c-sdhci driver on Samsung UniversalC210 board with dmabounce code enabled to force dma_alloc_coherent() use on each dma_map_* call (some of them are made from interrupts).
Best regards Marek Szyprowski Samsung Poland R&D Center
Changelog:
v2: - added support for atomic allocations (served from preallocated pool) - minor cleanup here and there - rebased onto v3.4-rc7
v1: http://thread.gmane.org/gmane.linux.kernel.mm/76703 - initial version
Patch summary:
Marek Szyprowski (4): mm: vmalloc: use const void * for caller argument mm: vmalloc: export find_vm_area() function mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping framework ARM: dma-mapping: remove custom consistent dma region
Documentation/kernel-parameters.txt | 4 + arch/arm/include/asm/dma-mapping.h | 2 +- arch/arm/mm/dma-mapping.c | 360 ++++++++++++++++------------------- include/linux/vmalloc.h | 10 +- mm/vmalloc.c | 31 ++-- 5 files changed, 185 insertions(+), 196 deletions(-)