On Tue, 23 Apr 2013, Clemens Ladisch wrote: > Alan Stern wrote: > > On Tue, 23 Apr 2013, Clemens Ladisch wrote: > >> Why is having a queue of two URB with one packet each suddenly not > >> allowed? > > > > It _is_ allowed when URB_ISO_ASAP is clear. I have never fully > > understood why the audio driver sets that flag. By setting it, you are > > telling the host controller driver that you are willing to give up > > reduced latency in order to avoid underruns. > > This flag was needed to avoid having to set urb->start_frame. Ah, okay. It is now unnecessary to set urb->start_frame; in fact that field is now output-only. (To be fair, I haven't checked _all_ the HCDs in this regard, just uhci-hcd, ohci-hcd, and ehci-hcd. However, if any other HCD requires urb->start_frame to be set then that HCD should be considered buggy and should be fixed.) > With the changed queueing API, the audio driver needs to change too. > I'll look into this ... Let me know if you have any questions. Alan Stern -- 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
