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linux userspace dma access for memory memory copy

linux userspace dma access for memory memory copy  using -'c,linux,kernel,dma,userspace'

My embedded ARM device has a 800x480 16 bit Linux framebuffer LCD which needs to be double-buffered manually.
At the moment I'm just using memcpy() to write the double buffer to the framebuffer which is awfully slow. A while(1){memcpy(lfb,dbuf)} loop maxes out the CPU at 100% and updates at approx 40 FPS.

The ARM device I'm using, and the Linux kernel does support DMA memory-memory copy, but I'm having trouble working out how I can access this in a userspace program.

It seems linux/dmaengine.h and dma_async_memcpy_buf_to_buf() is what I need to use, but it appears these are only available from within the kernel?

asked Sep 9, 2015 by CandyClickse
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