Configuring EtherCAT Distributed Clocks using HWI instead of Tasks on AM335x

Update: I managed to get D.C. SYNC functionality working with HWI's... it seems most of the compiler errors I reported were a result of ALSO trying to port PDI functionality to a HWI.

To get Sync0Isr running as a HWI, I did the following:

1. In tiescbsp.h, remove (comment out) the line that reads #define ENABLE_SYNC_TASK (as per instructions in the EtherCAT Firmware Guide)
2. In tiescbsp.c in function bsp_start_esc_isr, add curly braces around the following code (around lines 1288)
   

       uint32_t evtOutNum = HOST_SYNC0_EVENT - 20;
       sync0IsrArgs = (PRUICSS_IrqArgs* )malloc(sizeof(PRUICSS_IrqArgs));
       sync0IsrArgs->handle = pruIcssHandle;
       PRUICSS_registerIrqHandler(sync0IsrArgs,
                                  evtOutNum,
                                  pruIsrNum,
                                  1,           /* Used for C66x */
                                  0,
                                  &Sync0Isr);
   

   and

       uint32_t evtOutNum = HOST_SYNC1_EVENT - 20;
       sync1IsrArgs = (PRUICSS_IrqArgs* )malloc(sizeof(PRUICSS_IrqArgs));
       sync1IsrArgs->handle = pruIcssHandle;
       PRUICSS_registerIrqHandler(sync1IsrArgs,
                                  evtOutNum,
                                  pruIsrNum,
                                  1,           /* Used for C66x */
                                  0,
                                  &Sync1Isr);

   This will get rid of the compiler warnings "error: redefinition of 'evtOutNum'"

It looks like to get the SYNC functionality working there needs to be some minor code fixes to tiescbsp.c

However, I'm still observing jitter between the SYNC0 pulse from the PRUs and Sync0Isr; typically it responds to the SYNC0 pulse within 1.3 microseconds, but I've seen latency's as high as 6 microseconds, which is longer than my hard real-time deadline.  The ISR never responds quicker than 1 microsecond.

Where is the HWI actually declared in the code?  I see 'PRUICSS_registerIrqHandler' being called (code above), but I don't see a call to 'Hwi_create' anywhere.  Is a call to Hwi_create not necessary with PRUICSS interrupts?  What is the HWI priority of these Sync ISRs?