SPRZ450B February   2018  – September 2024 DRA74P , DRA75P , DRA76P , DRA77P

 

  1.   1
  2. 1Introduction
    1.     Related Documentation
    2.     Trademarks
    3.     Modules Impacted
  3. 2Silicon Advisories
    1.     Revisions SR 1.0 - Advisories List
    2.     i202
    3.     i378
    4.     i631
    5.     i694
    6.     i698
    7.     i699
    8.     i709
    9.     i727
    10.     i729
    11.     i734
    12.     i767
    13.     i782
    14.     i783
    15.     i802
    16.     i803
    17.     i807
    18.     i808
    19.     i809
    20.     i810
    21.     i813
    22.     i814
    23.     i815
    24.     i818
    25.     i819
    26.     i820
    27.     i824
    28.     i826
    29.     i829
    30.     i834
    31.     i849
    32.     i856
    33.     i862
    34.     i863
    35.     i869
    36.     i870
    37.     i871
    38.     i872
    39.     i874
    40.     i878
    41.     i879
    42.     i883
    43.     i889
    44.     i890
    45.     i893
    46.     i896
    47.     i897
    48.     i898
    49.     i899
    50.     i900
    51.     i903
    52.     i904
    53.     i916
    54.     i929
    55.     i930
    56.     i932
    57.     i933
    58.     i936
    59.     i940
    60.     i2446
  4. 3Silicon Limitations
    1.     Revisions SR 1.0 - Limitations List
    2.     i596
    3.     i641
    4.     i833
    5.     i838
    6.     i844
    7.     i845
    8.     i848
    9.     i876
    10.     i877
    11.     i892
    12.     i909
  5. 4Silicon Cautions
    1.     Revisions SR 1.0 - Cautions List
    2.     i781
    3.     i827
    4.     i832
    5.     i836
    6.     i839
    7.     i864
    8.     i885
    9.     i886
    10.     i912
    11.     i926
    12.     i931
    13.     i935
    14.     i937
  6. 5Revision History

i877

RGMII Clocks Should Be Enabled at Boot Time

CRITICALITY

Medium

DESCRIPTION

The RGMII 1000 Mbps Transmit timing is based on the output clock (rgmiin_txc) being driven relative to the rising edge of an internal clock and the output control/data (rgmiin_txctl/txd) being driven relative to the falling edge of an internal clock source. If the internal clock source is allowed to be static low (i.e., disabled) for an extended period of time then when the clock is actually enabled the timing delta between the rising edge and falling edge can change over the lifetime of the device. This can result in the device switching characteristics degrading over time, and eventually failing to meet the Data Manual Delay Time/Skew specs.

To maintain RGMII 1000 Mbps IO Timings, SW should minimize the duration that the Ethernet internal clock source is disabled. Note that the device reset state for the Ethernet clock is "disabled".

Other RGMII modes (10 Mbps, 100Mbps) are not affected.

WORKAROUND

If the SoC Ethernet interface(s) are used in RGMII mode at 1000 Mbps, SW should minimize the time the Ethernet internal clock source is disabled to a maximum of 200 hours in a device life cycle. This is done by enabling the clock as early as possible in IPL (QNX) or SPL/u-boot (Linux/Android) by setting the register CM_GMAC_CLKSTCTRL[1:0]CLKTRCTRL = 0x2:SW_WKUP.

In addition to programming SW_WKUP(0x2) on CM_GMAC_CLKSTCTRL, SW should also program modulemode field as ENABLED(0x2) on CM_GMAC_GMAC_CLKCTRL register.

If the application does not require Ethernet functionality ever, the developer can choose to place the GMAC module in a power disabled state CM_GMAC_GMAC_CLKCTRL.MODULEMODE = 0x0 (disabled) and CM_GMAC_CLKSTCTRL.CLKTRCTRL = 0x1 (SW_SLEEP) during the boot operation.

REVISIONS IMPACTED

SR 1.0

AM574x: 1.0

DRA75xP, DRA74xP, DRA77xP, DRA76xP: 1.0

TDA2Px: 1.0

AM576x: 1.0