On Friday 20 October 2006 12:10 am, Armen Baloyan wrote: > Hi all, > > During my work on ISOC EPs support implementation for USB OTG driver I've > met some difficulties - as is written in usb 2.0 spec: > > 5.12.4.1.2 Synchronous > > Synchronous endpoints can have their clock system (their notion of time) > controlled externally through SOF synchronization. These endpoints must > slave their sample clock to the 1 ms SOF tick (by means of a programmable > PLL). For high-speed endpoints, the presence of the microframe SOF can be > used for tighter frame clock tracking. > > This syncronization should be done in upper layer than PCD, i.e. in gadget,
That's not necessarily true, but gadget drivers should certainly be _able_ to do that synchronization. Remember also that there will be delays between the issuance of a SOF and issuance of its IRQ (likely that one's small), and also between issuance of that IRQ and its reception (function of system IRQ latency, which will be variable). > so I need to send SOF interrupt to gadget driver, which will make > synchronization via PLL. I couldn't find a way to do it without extending > Gadget API - can somebody tell me if there is method to do it without Gadget > API extneding and if yes, where I can find documentation with description of > that method. You'd need to extend the gadget API to do this. I'd suggest making it take an irqhandler_t ... do you have an ISO gadget driver in the works that will be using that synchronization though? I don't have any particular issue with adding such a mechanism, other than testability (and consequently getting all the gadget drivers to support the mechanism). - 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
