wolfgang gaerber

IMX28 ENET PTP Errata

Discussion created by wolfgang gaerber on Nov 5, 2013

Hi !

 

Found some more erratas concerning the PTP timer.

HW_ENET_MAC_ATIME_CTRL:

Depending on the selected clock - you need a delay between issue "capture" in this register - and reading HW_ENET_MAC_ATIME.

A delay from 2-3 clock cycles (as selected) is needed.

Without proper delay, read out ATIME gives corrupted values.

 

IRQs/event concurrency issue:

Having multiple ATIME IRQs sources (capture pps, 1ms tick, 250us periodic), firing around "0" of the interval - we observed that

comparator firing near "0" hangs up.

Running at 40Mhz with an increment of 25ns - we see that comparator events <25ns with a concurrent capture irq pending are stalled.

Workaround -> avoid comparator values < clockrate and raceconditions with simultaneous capture.

 

rgds.

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