title: dmatest.ko - how use it?
body: <p>I want to initiate a DMA-Transfer for testing.</p>
  
  <p>I stumbled accross a dmatest.c in the kernel sources (drivers/dma). I compiled a Kernel with this Module and tried it without any params.</p>
  
  <pre><code>sudo modprobe dmatest
  </code></pre>
  
  <p>and i get with dmesg</p>
  
  <pre><code>__dma_request_channel: fail ((null))
  </code></pre>
  
  <p>What are the prerequisites for dmatest.ko?
  Should I load a special DMA-Engine?
  Is a special param for dmatest.ko required (default should probe anything!?)?</p>