From: David Brownell [mailto:[EMAIL PROTECTED] Sent: Thursday, May 19, 2005 10:25 AM To: Borse, Ganesh
> how is it shown in sysfs? In any file? >>The current device configuration is bConfigurationValue, >>matching the USB spec. No, bConfigurationValue does not give any information about overcurrent condition. It shows whether device (the hub) is configured (value 1) or not (value 0). Also, file power/state does not contain this information. After going through USB2.0 Specs pdf, I came to know that GetPortStatus request provides an information for overcurrent (in the form a bit set to 0 or 1). This is explained in Tables 11-19 and 11-21 of USB2.0 specs. Accordingly, I created a test program and executed it on the bus powered 4-port external hub having bus powered devices on all 4 ports. All the time I got the wPortStatus value of 259 (from GetPortStatus IOCTL o/p). 259-decimal means bits 0, 1, and 8 are set. According to Table 11-21, bits 0, 1 signify that device is connected and port enabled. Bit 8 states that the given port is not in powered-off state. The bit 3 - PORT_OVER_CURRENT bit was never set. Why is this not reported on Port Status field, wPortStatus? Is this the limitation of Linux USB drivers? Windows correctly displays this information with pop-ups and alerts users about this. Also provides way of troubleshooting this condition by recommending moving devices to other ports. Thanks, Ganesh ------------------------------------------------------- This SF.Net email is sponsored by Oracle Space Sweepstakes Want to be the first software developer in space? Enter now for the Oracle Space Sweepstakes! http://ads.osdn.com/?ad_idt12&alloc_id344&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
