
ERR009742
Chip Errata for the i.MX 6Dual/6Quad and i.MX 6DualPlus/6QuadPlus, Rev. 6.1, 06/2016
82
NXP Semiconductors
Description:
When selected, the Write Context ID event (event 0x0B) of the Performance Monitoring Unit
(PMU) increments a counter whenever an instruction that writes to the Context ID register,
CONTEXTIDR, is architecturally executed. However this erratum means that an instruction that
reads the Context ID register also updates this counter.
The erratum can happen under the following conditions:
1. A PMU counter is enabled, by setting the PMCNTENSET.Px bit to 1 (x identifies a single event
counter, and takes a value from 0 to 7).
2. The “Write Context ID” event is mapped to this selected PMU counter:
a. The chosen PMU counter is selected, by setting PMSELR.SEL to x (the same value as in
condition 1).
b. The “Write Context ID” event is mapped to this selected PMU, by setting
PMXEVTYPER.evtCount to 0x0B.
3. The PMU is enabled, by setting the PMCR.E bit to 1.
4. A read access occurs to the CONTEXTIDR.
In this situation the PMU updates the counter when it should not.
Projected Impact:
The erratum affects the accuracy of the “Write Context ID" event, and its associated
PMUEVENT[12] output signal.
Workarounds:
There is no workaround for this erratum. The Freescale Linux BSP does not enable this optional
profiling feature by default. Users may add support for this profiling feature as required, but should
ensure the multiple ARM errata impacting the ARM PMU are considered.
Proposed Solution:
No fix scheduled
Linux BSP Status:
Software workaround is not implemented because this erratum will never be encountered in normal
device operation.The Freescale Linux BSP does not support this optional profiling feature.
ERR009742
ARM: 795769 - “Write Context ID" event is updated on read access