On Thu, 8 Jul 2004, Bernd Walter wrote: > On Thu, Jul 08, 2004 at 01:16:24AM -0700, Julian Elischer wrote: > > > > Matt Dillon just made a simple patch for this on Dfly and I'm looking at > > back-porting it. there is nothing in ugen that shouldn't let it take > > data from a bulk USB2 device at a good speed except that it doesn't ask > > There are technical limits - such as that we can't support select and > prereads without breaking generalness for bulk endpoints. yes but we can do better that 1KB per xfer :-) > > > for the data that fast.. it is possible that there is a problem in the > > ehci driver too, but I haven't got my mind around that driver quite > > fully enough yet to say for sure.. it looks like it doesn't allow more > > than one transfer per msec frame from the ugen device. solving this > > Possibly a side effect because we have to disconnect the pipe queue to > modify it, but I still think its the time we need to take the completed > xfer and setting up the next one. No, we get the same slowdown no matter how fast the machine is.. If doing this can give you a 60X slowdown then we must be doing it wrong.. Since we are the ONLY user of this bus, then there is nothing happenning on the sync schedule at the time we decide to do an xfer, and it should be halted. We should then add our 8 elements and kick it off, and then wait for the EOT interrupt. It is possible that the next transaction doesn't get started unil teh next frame boundary (as an alternate explanation) but either way it looks to me that something is slightly wrong in there.. > > > would allow the use of smaller buffers. I don;t think it's a problem > > woth overhead and small transfers, but rather that ugen is asking for > > only 1 x 1KB transaction per mSec when USB2 is capable of delivering > > 60KB/mSec. I think increasing the buffer size means still asking for one > > transaction per mSec, but it's a bigger transaction :-) > > What interrupt rate do you see from the host controller? yes, that occured to me earlier this evening and I'll check it tomorrow (thursday) when I have access to the hardware again.. > > -- > B.Walter BWCT http://www.bwct.de > bernd_at_bwct.de info_at_bwct.de > > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org" >Received on Thu Jul 08 2004 - 07:29:09 UTC
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