On Fri, Jul 15, 2011 at 3:58 PM, Kruno Mrak <kruno.mrak@xxxxxxxxxxxxxxxx> wrote: > Hi, > > when running our cameras on USB3.0 ports we get > "ERROR no room on ep ring". > This only happens if camera's image size is bigger than > ~1MB or when using multiple image buffers (queueing). > Capturing is made through libusb and async bulk transfers. > Now, as more and more of our customers are using PCIe-USB3.0 extension > cards we get under pressure. > After looking into xhci driver sources, i have seen that > TRBS_PER_SEGMENT is limited to 64 and segments per ep ring > is fixed to 1. (right?) For bulk transfer, it's 1 segment. Isochronous transfer needs a bigger ring because it inserts multiple TDs to the ring when an isoc URB is submitted. Currently it uses 8 segments. > Playing with this params (TRBS_PER_SEGMENT=256 and ep ring segments=8) > and first tests led to good results. > > So, my question is, do you agree with me that limited > ep ring allocation might cause above mentioned error. > Is there a chance to push development on ep ring allocation? > > Thank you in advance. > Maybe dynamic ring allocation helps in this situation. Thanks, Andiry -- 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
