On Thu, 12 Nov 2009, Shivdas Gujare wrote: > Thanks Pete, > > It stopped echo with BulkIn endpoint after I configured my minicom > with "S7=45 S0=0 L1 V1 X4 &c1 E0 Q0" The "E0" is what controls the echo. > but it stopped local echo in minicom, so I can't view what I am > typing, I will try to find out if there is any other option for local > echo with minicom. Now you know why the modem normally runs with "E1". It's so that you can see what you are typing. Why not just leave it turned on? > >> I hope this is a valid question, why do we need 32 byte limitation for > >> Control endpoint also? > > > > Why is this a concern? It was just a stop-gap measure until > > the binary API was on-line > > > > > Because, with 32 byte limitation, we can't capture complete response > to "GET_DESC CONFIGURATION" request mostly > for devices with more than one interface, Following are packets from 2 > interface CDC-ACM modem, > > with kernel usbmon, > > e08b8f00 2373631625 S Ci:1:006:0 s 80 06 0200 0000 0043 67 < > e08b8f00 2373632013 C Ci:1:006:0 0 67 = 09024300 02010580 fa090400 > 00010202 01060524 00010105 24010301 05240600 > > With userspace usbmon after removing 32 byte limitation, > > e08b8700 0.614517 S Ci:1:007:0 s 80 06 0200 0000 0043 67 < > e08b8700 0.614891 C Ci:1:007:0 0 67 = 09024300 02010580 fa090400 > 00010202 01060524 00010105 24010301 05240600 01042402 02070582 > 0310000a 09040100 020a0000 07070501 02000200 07058102 000200 > > If I understands correctly, this limitation is for skipping printing > huge bulk of raw data(such as 4096 bytes) from non-control endpoints, > which I am not sure is valid for control endpoint also. If you are concerned about receiving long control messages, use the userspace usbmon program. The reason for the 32-byte limitation on control endpoints is that it was easier to program a 32-byte limit on _all_ endpoints than to program the limit just for bulk endpoints. Thus, the kernel usbmon also has a 32-byte limit on interrupt and isochronous endpoints. 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
