On Sun, 7 Dec 2014, Florian Echtler wrote: > Hello everyone, > > I'm preparing to finally add support for the raw sensor video stream to > my driver for the SUR40 touchscreen. However, after an extensive amount > of Googling, I'm still not clear on the relationship between DMA > transfers, the USB core and the videobuf2 framework. > > Specifically, I'd like to know: > > - Can I always use DMA on the USB side (for bulk transfers), or does > this in any way require support from the USB device's hardware? (I'm > guessing no, but a definite answer would be great.)
DMA requires hardware support in the USB host controller, not in the USB device. Most current USB host controllers support DMA; only a few of the oldest ones don't. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
