Dear Alan, Do you mean if I usa a platform that is more faster, the issue may not occur , right? Thanks ! best Regards Soho 2011/6/1 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Tue, 31 May 2011, Soho Soho123 wrote: > >> Dear Laurent, >> ====================================================================================== >> Let me explain my problem again. >> We use MJPG-streamser to test IP Cam function. the network interface >> is WiFi. WebCam is using UVC driver. >> We have the issue is the stream will disconnect in a few minutes on >> our embedded system. >> the reason is : the call back function of uvc urb complete can not >> re-submit urb successfully. The error code is "-EFBIG". EHCI driver >> think the urb submit is too late. >> the ip cam test condition is 1280x720 30 fps via WiFi(802.11n). >> the call back function seems take more cpu cycles when itd_complete, >> because it decode data and re-submit urb . the call back function is >> included in ehci irq path. it may increase irq latency. >> Do you have idea about : >> is it "must" decode data in uvcvideo complete call back function? >> is it "must" re-submit urb in uvcvideo complete call back function? > > The callback routine must resubmit the URB. > > In theory the decoding could be delayed. But it would still require > the same amount of time. Although the latency might remain low, you > would probably find that uvcvideo has to drop some frames every now > and then. > > It's possible that your CPU simply isn't fast enough to keep up with > the video stream at this resolution. > > Alan Stern > > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
