On Sun, 16 Dec 2012, Vincent Pelletier wrote: > Le dimanche 16 décembre 2012 20:46:38, Vincent Pelletier a écrit : > > I checked the specs, and the warnings about wMaxPacketSize seem > > justified (although it's unclear to me wether wMaxPacketSize is > > restricted to exactly 512B in HS, or only upper-bound at 512B). > > Another reply to myself: > Tested USB device uses a Cypress FX2LP: > > http://www.summitsoftconsulting.com/picts/iti_pcb_top.jpg > > I checked the FX2LP specs, and endpoint 1 in both directions is hardwired to > wMaxPacketSize of 64. I believe the FX2LP is quite widespread (judging by the > availability of a GPL toolchain for it and two CLI tools to send its > firmware), so those warnings might cause redundant bug reports.
It does seem odd that people would buy and use these chips even though they are explicitly in violation of the USB specification. A device containing one of these things could never pass the USB-CV verification test. It may be possible for xhci-hcd to work around the bug (by internally changing wMaxPacketSize to 512). 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
