title: Making endpoint data buffers DMA able
body: <p>I am currently working on a custom hardware which has SH_MOBILE architecture. Hardware comes with USB(peripheral) and a DMAC having 2 channels.
  I am using R8a66597 UDC driver which is available in mainline kernel. I have added DMA related functions to the peripheral controller driver. Currently I am able to get the DMA working in TX path. But in RX path I am not able to use DMA, instead PIO is getting used. This is because the buffer address (buf in struct usb_request) is not 8 bit aligned.
  I would want to know how to ensure that these data transfer buffer is DMA able?</p>
  
  <p>Thanks in advance,
  Srinidhi KV</p>