JackOfAll wrote: > LOL. Greg, you really don't want to go there! I can give one example > where disk io, (especially on the Pi compared to other "similar" ARM > hardware), whereby using a lower speed (class) sdcard, requires > increasing buffer to a USB DAC, (doubling the settings I posted > earlier), to stay glitch free. May not be quite so much of an issue with > pico, but on my full-blown Fedora images which are writing to SDCARD a > lot more, (systemd journald and app logging while developing), and CPU > spending a lot of time in wait, waiting for IO to complete, it's most > definitely an issue, and without increasing buffer, a train wreck. > > I'd expect to get booed out of the thread, on the basis it's about a > software image that runs on Pi's, so I'll be careful how I put this, but > it wouldn't be too hard for me to suggest that anyone wanting to end up > with what I'd classify as a HQ audio music player, based on a USB > platform (and regardless of the DAC it's feeding), should stay the hell > away from the Pi. Gordon's FIQ work and P33M's complete re-write of the > USB driver, don't completely paper over the cracks. > > Other people have dropped breadcrumbs...... Take the P33M patch above. > Here's a quote from P33M when he was discussing Pi handling of ISO > transfers.... > > "To elaborate, support for USB1.1 Isochronous on Raspberry Pi has been > troublesome due to limitations with the hardware on BCM2835. It's not a > conventional USB host. In fact word from the original IP implementors is > that it was never intended to be used in this fashion, so Raspberry Pi > are basically "on their own" as far as support is concerned." > > The grief/quirkiness with ARM USB implementations has recently seen me > walking away from ARM (and using Bay Trail Intel NUC's) as the head unit > for a high-end USB DAC I've been working on. (Another project that may > or may not see the commercial light of day.)
Great insight. Does the implementation of add-on boards such as the HifiBerry circumvent these USB issues? ------------------------------------------------------------------------ SamS's Profile: http://forums.slimdevices.com/member.php?userid=9261 View this thread: http://forums.slimdevices.com/showthread.php?t=97803 _______________________________________________ unix mailing list unix@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/unix
