On Sat, 28 Sep 2013, Markus Rechberger wrote: > I hope the SG transfer does not introduce any latency issues we have > some usb chipsets which are very picky about latency issues on > embedded systems. The latency for SG transfers should be smaller than for non-SG. > We got it work by tuning the transfer size, if the timings are not met > the device will just disable the transfer. > Unfortunately it will take a second to detect that by the driver and > re-enabling the transfer which means that it will corrupt the data. > I do not have a good feeling about pushing SG transfers into the > kernel by modifying the legacy mode without having any experience with > it. While the idea behind SG transfers is definitely ok but who knows > how it will perform with such devices. The way to fix latency problems is by submitting multiple URBs, enough to make sure the I/O queue never empties out. Alan Stern -- 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
