Hello. On 13-04-2011 1:06, Janusz Krzysztofik wrote:
After switching from mem->dma_handle to virt_to_phys(mem->vaddr) used for obtaining page frame number passed to remap_pfn_range() (commit 35d9f510b67b10338161aba6229d4f55b4000f5b), videobuf-dma-contig
Please specify the commit summary -- for the human readers.
stopped working on my ARM based board. The ARM architecture maintainer, Russell King, confirmed that using something like virt_to_phys(dma_alloc_coherent()) is not supported on ARM, and can be broken on other architectures as well. The author of the change, Jiri Slaby, also confirmed that his code may not work on all architectures.
The patch tries to solve this regression by using virt_to_phys(bus_to_virt(mem->dma_handle)) instead of problematic virt_to_phys(mem->vaddr). I think this should work even if those translations would occure inaccurate for DMA addresses, since possible errors introduced by both translations, performed in opposite directions, should compensate.
Tested on ARM OMAP1 based Amstrad Delta board.
Signed-off-by: Janusz Krzysztofik<jkrzyszt@xxxxxxxxxxxx>
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