On Fri, 7 May 2010 10:51:10 -0400 (EDT) Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 7 May 2010, Daniel Mack wrote: > > > > At least the audio class and ua101 drivers don't do this and fill the > > > buffers before they are submitted. > > > > Gnaa, you're right. I _thought_ my code does it the way I described, but > > what I wrote is how I _wanted_ to do it, not how it's currently done. I > > have a plan to change this in the future. > > > > So unfortunately, that doesn't explain it either. Sorry for the noise. > > At one point we tried an experiment, printing out the buffer and DMA > addresses. I don't recall seeing anything obviously wrong, but if an > IOMMU was in use then that might not mean anything. Is it possible > that the IOMMU mappings sometimes get messed up for addresses above 4 > GB? You mean that an IOMMU could allocate an address above 4GB wrongly? If so, IIRC, all the IOMMU implementations use dev->dma_mask and dev->coherent_dma_mask properly. And the DMA address space of the majority of IOMMUs are limited less than 4GB. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
