> > > Either the data isn't getting written to the buffer correctly or else > > > the buffer isn't getting sent to the device correctly. Can anybody > > > suggest a means of determining which is the case? > > > > I can't say anything about this log that including only DMA addresses. > > I'm not familiar with how the USB core does DMA stuff. And the USB > > stack design that the USB core does DMA stuff (allocating, mappings, > > etc) makes debugging DMA issues really difficult. > > The DMA stuff is simple enough in this case. The urb->transfer_buffer > address is passed to dma_map_single(), and the DMA address it returns > is stored in urb->transfer_dma. Those are the two values printed out > by the debugging patch. Is that address (urb->transfer_dma) the same as 'virt_to_phys(urb->transfer_buffer)' (if not, then SWIOTLB is being utilized) and is the dma_sync_* done on the urb->transfer_dma (to properly sync the data from the SWIOTLB to the transfer_buffer) before you start using the urb->transfer_buffer? -- 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
