On Mon, Mar 25, 2002 at 01:46:57PM +0100, Georg Acher wrote: > On Mon, Mar 25, 2002 at 12:21:48PM +0000, Nick Craig-Wood wrote: > > The data stream gets corrupted in a very specific way - there are no > > bytes added or removed to the serial output but there is one byte > > overwritten with null (0x00) with 0,1 or 2 more corrupted bytes after > > it. > > Ouch... that looks like a problem for non-cacheline-sized transfers. Does it > also happen with 48bytes?
I satisfied myself that the problem transfer lengths were 32..62 bytes as passed to write(). 63 bytes transfer seemed to be OK as did 1..31 bytes. The driver adds 1 byte of length to the start of the packet. The max transfer size is 63 bytes. OK 2..32 bytes Bad 33..63 bytes OK 64 Bytes > > However (and this is what makes a simple bug report not so simple) the > > unpatched keyspan driver works absolutely perfectly on my desktop > > machine. On my laptop it doesn't give this error either but it spends > > so much time messing around in the BIOS with power management stuff > > that it is always dropping packets. > > Intel makes the "best" UHCIs with the least flaws... We have discovered that > by the hard way. For our DAB monitoring system via USB (384KB/s ISO > streaming) we only use mainboards with Intel chipsets. We have tried VIA and > SiS in the beginning, but they weren't as reliable for USB as Intel > mainboards and caused much trouble for us and our customers... Especially > VIA seems to have great problems with PCI-arbitration, there is > significantly more lost data in the streamed data, and the "famous" > IDE+Soundblaster-bug speaks for itself... Thank you for that advice - it has been noted well! We will need to order 20 motherboards soon so it will be worth our while searching for one with an Intel USB chipset I think. > > Does anyone have any more ideas as to what is going on or ideas as to > > what to try next? > > If there's a BIOS that's worth mentioning, have you tried to play a bit with > the PCI settings (posted write, buffering, latency, etc)? There is a quite normal BIOS. I'm afraid I don't normally play with these things in the BIOS - do you have any specific ideas (eg increase latency, disable buffering or something)? Thanks Nick -- Nick Craig-Wood [EMAIL PROTECTED] _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
