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ERR003756
Chip Errata for the i.MX 6Dual/6Quad and i.MX 6DualPlus/6QuadPlus, Rev. 6.1, 06/2016
148
NXP Semiconductors
Description:
The PCI Express Specification is unclear regarding the transmission of Idle Symbols when a
directed state transition occurs in the Recovery.Idle state. This can sometimes result in temporary
loss of synchronization between link partners when transitioning from L0 to Detect, through the
Disabled, Hot Reset, Configuration, or Loopback states.
Section 4.2.6.4.4 of the PCI Express Specification states that Recovery.Idle Transmitter sends Idle
data on all configured Lanes. Note: If directed to other states, Idle Symbols do not have to be sent
before transitioning to the other states (that is, Disable, Hot Reset, Configuration, or Loopback).
The PCI Express block chooses to send Idle symbols, as the specification does not prohibit the
sending of Idle symbols.
Projected Impact:
The device that initiates the state transition moves from Recovery.Idle through the requested state
and back to Detect. The remote partner moves from Recovery.Idle back to L0 state, without going
through the required state transition. The link partners lose synchronization. After a timeout period,
the link partner moves through the correct state transition, and the link resynchronizes.
The probability of occurrence of this issue depends on the link latency.
Workarounds:
None.
Proposed Solution:
No fix scheduled
Linux BSP Status:
Software workaround cannot be implemented to mask or workaround this SoC issue. This erratum
will result in impacted or reduced functionality as described above.
ERR003756
PCIe: 9000387484—LTSSM: Software-initiated transitions to
Disabled, Hot Reset, Configuration, or Loopback states sometimes
take longer than expected