David, Thanks for quick reply. Actually I don't have any Gadget driver that works with ISOC Transfers - I'm working on PCD. I need to implement ISOC transfers support and during my work I met discussing problem with SOF synchronization. I'm planning to implement some gadget driver for testing PCD. You wrote :
>> 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. So as I understood device clock synchronization may be done in PCD? Does it mean that I need to implement such a synchronization routine in PCD? Thanks in advance, Armen Baloyan ----- Original Message ----- From: "David Brownell" <[EMAIL PROTECTED]> To: <linux-usb-devel@lists.sourceforge.net> Cc: "Armen Baloyan" <[EMAIL PROTECTED]> Sent: Tuesday, October 24, 2006 11:52 PM Subject: Re: [linux-usb-devel] SOF sync and Gadget API > 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
