1. 20 1月, 2020 1 次提交
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  8. 28 12月, 2019 1 次提交
    • M
      net: stmmac: dwmac-meson8b: Fix the RGMII TX delay on Meson8b/8m2 SoCs · bd6f4854
      Martin Blumenstingl 提交于
      GXBB and newer SoCs use the fixed FCLK_DIV2 (1GHz) clock as input for
      the m250_sel clock. Meson8b and Meson8m2 use MPLL2 instead, whose rate
      can be adjusted at runtime.
      
      So far we have been running MPLL2 with ~250MHz (and the internal
      m250_div with value 1), which worked enough that we could transfer data
      with an TX delay of 4ns. Unfortunately there is high packet loss with
      an RGMII PHY when transferring data (receiving data works fine though).
      Odroid-C1's u-boot is running with a TX delay of only 2ns as well as
      the internal m250_div set to 2 - no lost (TX) packets can be observed
      with that setting in u-boot.
      
      Manual testing has shown that the TX packet loss goes away when using
      the following settings in Linux (the vendor kernel uses the same
      settings):
      - MPLL2 clock set to ~500MHz
      - m250_div set to 2
      - TX delay set to 2ns on the MAC side
      
      Update the m250_div divider settings to only accept dividers greater or
      equal 2 to fix the TX delay generated by the MAC.
      
      iperf3 results before the change:
      [ ID] Interval           Transfer     Bitrate         Retr
      [  5]   0.00-10.00  sec   182 MBytes   153 Mbits/sec  514      sender
      [  5]   0.00-10.00  sec   182 MBytes   152 Mbits/sec           receiver
      
      iperf3 results after the change (including an updated TX delay of 2ns):
      [ ID] Interval           Transfer     Bitrate         Retr  Cwnd
      [  5]   0.00-10.00  sec   927 MBytes   778 Mbits/sec    0      sender
      [  5]   0.00-10.01  sec   927 MBytes   777 Mbits/sec           receiver
      
      Fixes: 4f6a71b8 ("net: stmmac: dwmac-meson8b: fix internal RGMII clock configuration")
      Signed-off-by: NMartin Blumenstingl <martin.blumenstingl@googlemail.com>
      Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      bd6f4854
  9. 21 12月, 2019 1 次提交
  10. 19 12月, 2019 17 次提交