On Sun, Jun 23, 2013 at 11:34 PM, Bas Wijnen <[email protected]> wrote: > Hi, > > On Sun, Jun 23, 2013 at 11:14:44PM +0200, richard -rw- weinberger wrote: >> USB Device does not have DMA support and is therefore very slow. >> Also the USB mass storage gadget seems to need DMA. > > I've successfully implemented mass storage on Iris without DMA (I don't > have support for DMA in Iris yet). I don't know if Linux requires it, > though.
Last time I went though the sources I noticed that DMA is mandatory. But I want DMA in any case to have a _fast_ storage gadget. >> The Linux driver supports it, but it is disabled by default and if I enable >> DMA USB Devices does not work at all. >> >> Now I'm wondering, is this a known issue? > > It wasn't known to me, but that doesn't mean much. > >> Is DMA for the UDC just broken in HW? > > I would not expect this. However, it is quite possible that the > implementation has a bug; the SoC's programmers manual is not always > easy to understand. The JZ BSP seems to support DMA, the USC driver has a switch to enable/disable DMA. In the NanoNode sources this switch is by default off... Thanks, //richard _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
