On Tue, May 27, 2008 at 4:01 PM, Nicolas <nicolas.martin at freesurf.fr> wrote: > > Le mardi 27 mai 2008 ? 15:42 -0400, m. allan noah a ?crit : >> On Tue, May 27, 2008 at 3:29 PM, Nicolas <nicolas.martin at freesurf.fr> >> wrote: >> > Le lundi 26 mai 2008 ? 19:12 -0400, m. allan noah a ?crit : >> >> two random thoughts- >> >> >> >> 1. can he try 32 bit kernel on same exact machine, just to rule out >> >> hardware problems? >> > >> > Good point, and to try other USB ports on the same machine, that needs >> > to be confirmed first as it could be a HW issue >> > >> >> 2. is there a pattern to the timeouts, like always same number of >> >> errors before a good packet? >> > >> > It looks to be a repetitive pattern, i.e. error occurs on a second >> > "read" sequence when reading image data, but occurs also sometimes with >> > smaller transaction control messages (write message, then read response >> > immediately). >> > I've asked to give a try with a small tempo between two successive image >> > data readings, but do not have feedback yet. >> > >> > Thanks >> > >> >> yes- it could be that his machine is too fast for the scanner, not >> that it is 64 bits. >> >> allan > > But this would mean that with machines getting faster and faster, > something needs to be adjusted, so that consecutive usb commands do not > occur within a too short delay. > > Unfortunately, I did not see any spec for such timings in libusb. > Maybe something about that is the usb spec ? need to check this point... > > Nicolas >
there is no way to control this in libusb AFAIK, instead, you would have to determine a dynamic delay period to add before all commands. allan -- "The truth is an offense, but not a sin"
