On Tuesday 09 May 2006 9:08 pm, Juhee MALA wrote: > > Thanks for your answers. Just one question, when we use the URB_NO_INTERRUPT > flag, does it inhibit the interrrupt for non-error completions only? or does > it inhbit all the interrupts? If it inhibits all the interrupts how can we > monitor the status?
It's a hint, and may not change the semantics. The flag is allowed to change performance characteristics only. If the HCD can't do that, it must ignore the hint. > The application we are using is the zero gadget driver, for testing our > host. Actually I just wanted to know what is the maximum speed that anybody > would have seen with the URB size of 8KByte, or is the theoretical value > actually achievable? > > The host controller that we are using is Synopsys EHCI controller. And the peripheral controller is ... ? Remember the host can't shuffle data any quicker than the peripheral. At high speed, 8 KB is 16 bulk packets, a full microframe plus three packets into the next frame. Good luck actually achieving that throughput, but call it two microframes per buffer with normally quick hardware and software on both sides of the interaction. In the normal mode, gadget zero is single buffered. So the absolute best case for IN traffic involves the peripheral issuing a completion IRQ when the FIFO fills, and being able to reissue its TX usb_request and queue the next DMA to that FIFO before that fifo empties ... about 10usec, which is not unachievable. OUT traffic is a bit harder to model, but in the best case it's comparable; unfortunatly peripheral hardware rarely seems to get near such best cases for OUT transfers. - Dave ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
