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isoc transactions in 2.3.9 vs 2.3.8


I have a USB (1.1) device which sends data up an
isoc pipe.  The data is bursty, so most/all of the isoc
packets are short.

The attached user space code frag reads the pipe.
(It's derived from the 'simple' example from Apple)

It works fine under 10.3.8, but not on a 10.3.9
system.  After about 20 seconds, the initial read
requests complete with underrun's (this is normal,
actually, but the completion should be called in a
more timely manner!)

However, the code works fine if a USB mouse is
moving at all times.  If the mouse stops moving, the
requests stop flowing.

Does anyone have any ideas?

Jim Chapman

--------------------

#define ISO_PIPEREF 5             // iso pipe
#define ISO_PIPESIZE 512        //  iso endpoint packet size
#define ISO_REQCOUNT 10     // concurrent active requests
#define ISO_REQFRAMES  10  // frames per request
#define ISO_FUTURE  10           // delay to first frame

#define FRAME_COUNT 10000

mach_port_t 	masterPort = 0;				// requires <mach/mach.h>
unsigned        frameCounter = 0;
UInt64          nextFrame;

typedef struct
{
        IOUSBInterfaceInterface **interface;
        IOUSBIsocFrame frames[ISO_REQFRAMES];
        unsigned char buffer[ISO_REQFRAMES * ISO_PIPESIZE];
} IsoRequest;

static IsoRequest isoRequests[ISO_REQCOUNT];

void isoCallback(void *dummy, IOReturn result, void *arg0)
{
    IsoRequest *r = (IsoRequest *)dummy;
    unsigned j;
    IOReturn err;

printf("isoCallback: %d, %08x, %d\n", (int)dummy, result, (int)arg0);

    if(result != kIOReturnSuccess && result != kIOReturnUnderrun)
    {
        CFRunLoopStop(CFRunLoopGetCurrent());
        return;
    }

    /*
    if(++frameCounter >= FRAME_COUNT)
    {
        CFRunLoopStop(CFRunLoopGetCurrent());
        return;
    }
    */

    for(j=0;j<ISO_REQFRAMES;j++)
    {
        r->frames[j].frStatus=2;
        r->frames[j].frReqCount=ISO_PIPESIZE;
        r->frames[j].frActCount=0;
    }

err = (*(r->interface))->ReadIsochPipeAsync(r->interface,ISO_PIPEREF,r- >buffer,nextFrame,ISO_REQFRAMES,r->frames, isoCallback, r);
if (err)
{
printf("isoCallback: ReadISochPipeAsync failed, err = %08x\n", err);
CFRunLoopStop(CFRunLoopGetCurrent());
return;
}

    nextFrame+=ISO_REQFRAMES;
}

void startISO(IOUSBInterfaceInterface **intf)
{
    IOReturn	err;			
    UInt8	direction, number, transferType, interval;
    UInt16	maxPacketSize;
    unsigned    i,j;
    AbsoluteTime time;
    CFRunLoopSourceRef source;

err = (*intf)->GetPipeProperties(intf, ISO_PIPEREF, &direction, &number, &transferType, &maxPacketSize, &interval);
if (err)
{
printf("startISO: unable to get pipe properties for pipe %d, err = %08x\n", ISO_PIPEREF, err);
return;
}

if(transferType!=kUSBIsoc || interval!=1 || maxPacketSize!=ISO_PIPESIZE || direction!=kUSBIn)
{
printf("startISO: pipe %d is unexpected type\n", ISO_PIPEREF);
return;
}

    printf("startISO: pipe %d is OK\n", ISO_PIPEREF);

err = (*intf)->CreateInterfaceAsyncEventSource(intf, &source);
if (err)
{
printf("transferData: unable to create event source, err = %08x\n", err);
return;
}

CFRunLoopAddSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode);

err = (*intf)->GetBusFrameNumber(intf,&nextFrame,&time);
if (err)
{
printf("transferData: can't get current frame, err = %08x\n", err);
CFRunLoopRemoveSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode);
return;
}

    nextFrame += ISO_FUTURE;
    frameCounter = 0;

    for(i=0;i<ISO_REQCOUNT;i++)
    {
        isoRequests[i].interface = intf;

        for(j=0;j<ISO_REQFRAMES;j++)
        {
            isoRequests[i].frames[j].frStatus=2;
            isoRequests[i].frames[j].frReqCount=ISO_PIPESIZE;
            isoRequests[i].frames[j].frActCount=0;
        }

err = (*intf)- >ReadIsochPipeAsync(intf,ISO_PIPEREF,isoRequests[i].buffer,nextFrame,ISO _REQFRAMES,isoRequests[i].frames, isoCallback, &isoRequests[i]);
if (err)
{
printf("transferData: ReadISochPipeAsync failed, err = %08x\n", err);
CFRunLoopRemoveSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode);
return;
}

        nextFrame+=ISO_REQFRAMES;
    }

    printf("starting runloop\n");
    CFRunLoopRun();
    printf("runloop exited\n");

CFRunLoopRemoveSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode);
}

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