Intel® Stratix® 10 TX Device Errata

ID 683470
Date 7/21/2022
Public
Document Table of Contents

3.13. 851871: ETM May Lose Counter Events While Entering WFx Mode

Description

If the ETM resources become inactive because of a low-power state, there is a one-cycle window during which the counters and the sequencer may ignore counter-at-zero resources.

The following sequence is required for this erratum to occur:

  1. The core executes a WFI or WFE instruction.
  2. The ETM enters a low-power state.
  3. In a one-cycle window around this point, either:
    1. A counter in self-reload mode generates a counter-at-zero resource.
    2. A counter in normal mode gets a RLDEVENT on the cycle in which it has just transitioned to zero.
  4. A counter or sequencer is sensitive to the counter-at-zero resource.

Impact

Counters sensitive to a counter-at-zero resource may not reload or decrement. If the sequencer is sensitive to a counter-at-zero resource, it may not change state, or may change to an incorrect state.

Workaround

The ETM can be prevented from entering low-power mode by setting the LPOVERRIDE bit of Trace Event Control 1 (TRCEVENTCTL1R) register. This workaround is only needed if there is a counter or sequencer sensitive to a counter-at-zero resource.

Category

Category 3

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