SPRZ429N July   2014  – July 2024 AM5726 , AM5728 , AM5729

 

  1.   1
  2. 1Introduction
    1.     Related Documentation
    2.     Trademarks
    3.     Modules Impacted
  3. 2Silicon Advisories
    1.     Revisions SR 2.0, 1.1 - Advisories List
    2.     i202
    3.     i378
    4.     i631
    5.     i694
    6.     i698
    7.     i699
    8.     i727
    9.     i729
    10.     i734
    11.     i767
    12.     i782
    13.     i783
    14.     i802
    15.     i803
    16.     i807
    17.     i808
    18.     i809
    19.     i810
    20.     i813
    21.     i814
    22.     i815
    23.     i818
    24.     i819
    25.     i820
    26.     i824
    27.     i826
    28.     i829
    29.     i834
    30.     i837
    31.     i840
    32.     i841
    33.     i842
    34.     i843
    35.     i847
    36.     i849
    37.     i852
    38.     i854
    39.     i855
    40.     i856
    41.     i859
    42.     i861
    43.     i862
    44.     i863
    45.     i868
    46.     i869
    47.     i870
    48.     i871
    49.     i872
    50.     i874
    51.     i875
    52.     i878
    53.     i879
    54.     i880
    55.     i882
    56.     i883
    57.     i884
    58.     i887
    59.     i889
    60.     i890
    61.     i893
    62.     i895
    63.     i896
    64.     i897
    65.     i898
    66.     i899
    67.     i900
    68.     i901
    69.     i903
    70.     i916
    71.     i927
    72.     i929
    73.     i930
    74.     i932
    75.     i933
    76.     i936
    77.     i940
    78.     i2446
  4. 3Silicon Limitations
    1.     Revisions SR 2.0, 1.1 - Limitations List
    2.     i596
    3.     i641
    4.     i833
    5.     i838
    6.     i845
    7.     i848
    8.     i850
    9.     i851
    10.     i853
    11.     i857
    12.     i858
    13.     i876
    14.     i877
    15.     i892
    16.     i909
    17.     i922
    18.     i925
  5. 4Silicon Cautions
    1.     Revisions SR 2.0, 1.1 - Cautions List
    2. 4.1 106
    3.     i827
    4.     i832
    5.     i836
    6.     i839
    7.     i864
    8.     i885
    9.     i886
    10.     i912
    11.     i926
    12.     i931
    13.     i935
  6. 5Revision History

i2446

PRU-ICSS: Express bus initialization recommendation

Details:

The affected SoCs includes two instances of ICSS (ICSS1 and ICSS2). There is a bus connection from ICSS1 to ICSS2 and from ICSS2 to ICSS1. This bus logic requires a synchronous reset (clocks to be enabled) to drive a known state on its outputs. If clocks are not enabled to ICSS1 in software, then depending on the random state of the ICSS1 output bus, it may continuously issue Read or Write transactions to ICSS2 resulting in corruption of the ICSS2 module. The same situation can happen in reverse if ICSS1 is enabled and ICSS2 clocks are not on.

The power-up state of the critical control signals on each bus tends to settle to 0-state, but that is not guaranteed without a proper reset. This is why the issue may not be observed on all systems or may have different fail modes from system to system.

Workaround(s):

If a single ICSS module is used in a customer system, then clocks to the other ICSS module should be enabled first – this results in the ICSS module that is being used having proper deasserted state on the input bus before it is enabled.

If both ICSS modules are used in a system, then software can use the EDMA controller to issue an atomic write to the clock enable registers such that the two ICSS modules clocks are turned on within 20ns of each other.

Pseudo-code for a system that uses only ICSS2 or ICSS1 is shown here:

// CM_L4PER2_PRUSS1_CLKCTRL and CM_L4PER2_PRUSS2_CLKCTRL

/* Example #1 if ICSS2 used (ICSS1 not used) */

// Enable ICSS1 clock – ICSS1 state may be corrupted as ICSS2 is powered off now

*(volatile uint32_t*)(0x4A009718) = 0x00000002;

// Enable ICSS2

*(volatile uint32_t*)(0x4A009720) = 0x00000002;

/* Example #2 if ICSS1 usage (ICSS2 not used) */

// Enable ICSS2 clock – ICSS2 state may be corrupted as ICSS1 is powered off now

*(volatile uint32_t*)(0x4A009720) = 0x00000002;

// Enable ICSS1

*(volatile uint32_t*)(0x4A009718) = 0x00000002;

If a system uses both ICSS1 and ICSS2, contact your TI representative for an SDK patch that implements the EDMA workaround.