Dec. 20, 2016
9:38 a.m.
On Mon, Dec 19, 2016 at 06:08:47PM +0200, Ran Shalit wrote:
Hello,
I want to use DMA from userspace.
Why?
I already use dma in kernel, and now I want can create a character device which will be responsible for this.
Why?
The only problem is that I want to use the same memory which was allocated in kernel with dma_alloc_coherent.
Why?
Is it correct to use mmap in order to use the phsyical memory which was allocated with dma_alloc_coherent ?
If it's that simple it can be surely helpful, and the simple driver which wraps dma_alloc_coherent can do the job for dmaing from userspace.
Have you looked at the uio driver interface? But again, why? What problem are you trying to solve here? thanks, greg k-h