On Tue, 2006-01-24 at 10:53 -0500, Alan Stern wrote: > > That having been said, you should note that almost none of the USB > controller hardware found in desktop/laptop computers and a surprisingly > small percentage of external hubs support port power control. (I say > surprisingly because power control is a requirement in the USB 2.0 spec, > so to me anything less than 100% is surprising.)
This is an Atmel AT43312A 4 port hub on an embedded device, which looks like it should support per-port power switching (it also looks like that from the schematic, though we haven't tried it). But the current issue is that the flash device on the port sometimes does not respond to the initial GET_DESCRIPTOR, and we're interested in at least checking whether there's some sequence involving (say) power off and on of the port that will clear this condition. We'd rather not hack the hub code, so the question still stands: if the hardware supports this, is there a simple way of doing this from user space (e.g., /sys) to the questionable port only? > > By the way, does your flash device sometimes fail to enumerate when > attached to a host running Windows? Do you have any idea why it fails to > enumerate? Is it something wrong with the device or something that needs > to be fixed in the Linux stack? The Windows suggestion is a good one; I'll see if we can try it. We're trying to diagnose what's going on; obviously if it's a Linux stack problem we'll try to pass either a bug report or a fix upstream. FWIW, the device we're having most issues with is reported as a ID 0ea0:2168 Ours Technology, Inc. Transcend JetFlash 2.0 / Astone USB Drive ,which also shows up in the unusual_devs.h list. Thanks, sf ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=103432&bid=230486&dat=121642 _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
