>>> I have run across this quote a couple of times : >>> "Almost all USB-serial (Even ExpressCard) have speed >>> limitations on Linux/Solaris due to a cap on the driver. (512k/s)" >>> Using a Sierra 881 HSDPA modem on a TP61p, I get somewhat upside down >>> throughput >>> figures doing a speed test -- Download : ~400k/s Upload : ~1200k/s. >>> >>> Would someone be able to shed some light on this Cap feature and the >>> implications of >>> removing it / patching the code. >> I designed USB serial interfaces for Solaris and wrote a few drivers and >> I'm not aware of any such thing. The driver always propagates data to >> the application as soon as it receives it; same for transmit. If there >> is any artificial capping at all, it must be on the device side. > > Please. With Windows and Linux, I could get something like 300-400 > Kbytes/second > using a Pantech PX-500. The best I ever saw on Solaris was on the order of > 100Kbytes/second.
You can always look at the code if you have reasons not to believe me. There are no *artificial* delays in the usbsacm and usbser modules between getting a callback from the USB framework and pushing the message block upstream. That's all I'm saying. I'm not saying the performance is stellar, it obviously isn't. But that wasn't the OP's question. -Artem
