> -----Original Message----- > From: Bjørn Mork [mailto:bj...@mork.no] > > We normally avoid sending ZLPs by padding NTBs with a zero byte if the > NTB is shorter than dwNtbOutMaxSize, resulting in a short USB packet > instead of a ZLP. But in the case where the NTB length is exactly > dwNtbOutMaxSize and this is an exact multiplum of wMaxPacketSize, then > we must send a ZLP. > > This fixes an issue seen on a Sierra Wireless MC7710 device where the > transmission would fail whenever we ended up padding the NTBs to max > size.
If you add ZLP for NTBs of dwNtbOutMaxSize, you are heavily affecting CPU load, increasing interrupt load by factor of 2 in high load traffic scenario and possibly decreasing throughput for all other devices which behaves correctly. Why should others pay for Sierra Wireless fault? At least, do check VID/PID in usbnet and send ZLP only for malfunctioning devices. Regards, Alexey
