title: Set mmc2 on beaglebone black
body: <p>I am working with a Beaglebone Black and I would like to use the mmc2 slot.</p>
  
  <p>according to AM335xx TRM, a beaglebone black should have 3 mmc available:
   mmc0 (sd card);
  mmc1 (2G flash),
   mmc2.</p>
  
  <p>I am trying to enable mmc2 by device tree (and I am quite sure to have the right pin settings) but, by doing
  dmesg
  I obtain:</p>
  
  <pre><code>/ocp/mmc@47810000: can't find DMA channel
   omap_hsmmc mmc.11: unable to obtain RX DMA engine channel 65
  </code></pre>
  
  <p>By putting the oscilloscope probe on the header (e.g. the mmc2 clk signal), I do not see any transition.
  I already removed R 160 to have mmc2 cmd accessible but I do not see any transition also there.</p>
  
  <p>I tried both to enable it by </p>
  
  <pre><code> echo &gt; /sys/devices/..../slots
  </code></pre>
  
  <p>and by      </p>
  
  <pre><code>  capemgr.enable_partno
  </code></pre>
  
  <p>with no success:
  I can see it in </p>
  
  <pre><code>/sys/devices/..../slots
  </code></pre>
  
  <p>(with the L meaning loaded)..but no way to see any signal on the header.</p>
  
  <p>I already googled it but answers are not clear at all.
  Any ideas?</p>
  
  <p>My    </p>
  
  <pre><code> uname -a
  </code></pre>
  
  <p>is:</p>
  
  <pre><code>Linux beaglebone 3.8.13 #1 SMP Tue Jun 18 02:11:09 EDT 2013 armv7l GNU/Linux
  </code></pre>
  
  <p>Thanks for your help.</p>