On Sun, Mar 13, 2016 at 04:46:07PM +0100, Oleksij Rempel wrote: > Am 13.03.2016 um 16:30 schrieb Alan Stern: > > On Sun, 13 Mar 2016, Oleksij Rempel wrote: > > > >> Hallo all, > >> > >> i need to sync device clock with host clock, since device will return > >> SOF counter for each packet i need to use it as reference. Are there any > >> proper way to convert SOF to a host timestamp? > > > > No, there isn't. There is no relationship between the SOF packet > > arrival time or frame number and the host's time. > > > > Alan Stern > > > > Hm... Usb Vidoe Class specification suggest to use Source Time Clock > (some internal clock) value connected with SOF number to get actual > Frame timestamp. At same time bDealy from audio descriptor should be > used to sync audio and video. If i see it correctly, bDelay is expressed > in SOF or milliseconds as well. So if only way to Sync both streams is > SOF, how can it be made? > Is it possible to get at least SOF number of received packet? > Standard EHCI does not include SoF interrupt at USBINTR, so the EHCI stack doesn't have the code to handle it. If your vendor IP supports something like (SOF Received Interrupt Enable) interrupt at USBINTR, you can use it to compute the SoF number. -- Best Regards, Peter Chen -- 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
