> Subject: Re: Problem with non aligned DMA in usbnet on ARM I remain unconvinced the bug is anywhere except in whatever host controller is rejecting the buffers it's given. Does anyone have proof the bug is elsewhere? Think for a moment what chaos the kernel would be if arbitrary subsystems were allowed to introduce random DMA alignment "requirements". It would not be possible to pass buffers between subsystems with any success at all... > > 1) Require that usb drivers submit buffers obtained > from kmalloc() and > friends Requirements are already documented with the Description of what memory is DMA-able. It's not kmalloc() specifically that's required. with no extra offsets. Offsets have nothing to do with being DMA-able. They might have to do with working around hardware flaws though. (ISTR PXA255 also had a 32-bit goof, making its DMA engine unusable for most purposes.) > > 2) Require that usb_submit_urb() accept byte aligned buffers. I believe we already require that. Of course, the requirement is on HCDs, not on that call. -- 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
