The applications code calls IOKit at application level; no kernel
code is used.
(...)
About once or twice a week, the USB port I am using will appear to
die. The IORegistryExplorer no longer "sees" our device, and it no
longer "sees" other devices plugged into that port. Powering down
everything, waiting a few minutes, and powering everything up
appears to restore normal operation.
(...)
Has anyone experienced anything like this? Does anyone know of
softwares sins (or USB protocol sins) that would cause OS X to
decide to quit paying attention to a USB port, or something like that?
I was able to verify that my Macs' USB port stops working when
running Apple's USB SimpleExample sample code in a loop. So I second
your guess that it is a software issue.
You might want to verify using attached slightly modified
USBSimpleExample's main() function with a bulk USB device of your
choice connected to your Mac.
Just adjust vendorID/productID appropriately, then call the tool from
the command line and let it do its device arbitrition work a couple
of thousand times. On my PB G4 17" 1.67 GHz (Mac OS X 10.4.6) it took
~10k loops to make the USB port my bulk device is connected to stop
working (also, the USBSimpleExample application cannot be killed and
hangs around until reboot).
Some months ago (running Panther iirc), I verified this behaviour on
a Dual-G4 867 MHz, an iBook G3 600 MHz and a PM G5 1.6GHz.
int main (int argc, const char * argv[])
{
int i, loopCount = (argc > 1) ? atoi(argv[1]) : 10000; /
*MODIFICATION*/
for (i = 1; i <= loopCount; i++){ /*MODIFICATION*/
kern_return_t err;
CFMutableDictionaryRef matchingDictionary = 0; // requires
<IOKit/IOKitLib.h>
SInt32 idVendor = 0x04A9; // Canon /*MODIFICATION*/
SInt32 idProduct = 0x105C; // S400 /*MODIFICATION*/
CFNumberRef numberRef;
io_iterator_t iterator = 0;
io_service_t usbDeviceRef;
printf("\nLOOP # %d of %d\n", i, loopCount); /*MODIFICATION*/
err = IOMasterPort(MACH_PORT_NULL, &masterPort);
if (err)
{
printf("USBSimpleExample: could not create master port, err = %
08x\n", err);
return err;
}
matchingDictionary = IOServiceMatching(kIOUSBDeviceClassName); //
requires <IOKit/usb/IOUSBLib.h>
if (!matchingDictionary)
{
printf("USBSimpleExample: could not create matching dictionary\n");
return -1;
}
numberRef = CFNumberCreate(kCFAllocatorDefault,
kCFNumberSInt32Type, &idVendor);
if (!numberRef)
{
printf("USBSimpleExample: could not create CFNumberRef for vendor
\n");
return -1;
}
CFDictionaryAddValue(matchingDictionary, CFSTR(kUSBVendorID),
numberRef);
CFRelease(numberRef);
numberRef = 0;
numberRef = CFNumberCreate(kCFAllocatorDefault,
kCFNumberSInt32Type, &idProduct);
if (!numberRef)
{
printf("USBSimpleExample: could not create CFNumberRef for
product\n");
return -1;
}
CFDictionaryAddValue(matchingDictionary, CFSTR(kUSBProductID),
numberRef);
CFRelease(numberRef);
numberRef = 0;
err = IOServiceGetMatchingServices(masterPort,
matchingDictionary, &iterator);
matchingDictionary = 0; // this was consumed by the above call
while ( (usbDeviceRef = IOIteratorNext(iterator)) )
{
printf("Found device %p\n", (void*)usbDeviceRef);
dealWithDevice(usbDeviceRef);
IOObjectRelease(usbDeviceRef); // no longer need this reference
}
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