• Takeshi Kihara's avatar
    arm64: dts: renesas: ebisu: Remove renesas, no-ether-link property · ae8ff9c5
    Takeshi Kihara authored
    [ Upstream commit 90d4fa39 ]
    
    It is incorrect to specify the no-ether-link property for the AVB device on
    the Ebisu board. This is because the property should only be used when a
    board does not provide a proper AVB_LINK signal. However, the Ebisu board
    does provide this signal.
    
    As per 87c059e9 ("arm64: dts: renesas: salvator-x: Remove renesas,
    no-ether-link property") this fixes a bug:
    
        Steps to reproduce:
        - start AVB TX stream (Using aplay via MSE),
        - disconnect+reconnect the eth cable,
        - after a reconnection the eth connection goes iteratively up/down
          without user interaction,
        - this may heal after some seconds or even stay for minutes.
    
        As the documentation specifies, the "renesas,no-ether-link" option
        should be used when a board does not provide a proper AVB_LINK signal.
        There is no need for this option enabled on RCAR H3/M3 Salvator-X/XS
        and ULCB starter kits since the AVB_LINK is correctly handled by HW.
    
        Choosing to keep or remove the "renesas,no-ether-link" option will have
        impact on the code flow in the following ways:
        - keeping this option enabled may lead to unexpected behavior since the
          RX & TX are enabled/disabled directly from adjust_link function
          without any HW interrogation,
        - removing this option, the RX & TX will only be enabled/disabled after
          HW interrogation. The HW check is made through the LMON pin in PSR
          register which specifies AVB_LINK signal value (0 - at low level;
          1 - at high level).
    
        In conclusion, the present change is also a safety improvement because
        it removes the "renesas,no-ether-link" option leading to a proper way
        of detecting the link state based on HW interrogation and not on
        software heuristic.
    
    Fixes: 8441ef64 ("arm64: dts: renesas: r8a77990: ebisu: Enable EthernetAVB")
    Signed-off-by: default avatarTakeshi Kihara <takeshi.kihara.df@renesas.com>
    [simon: updated changelog]
    Signed-off-by: default avatarSimon Horman <horms+renesas@verge.net.au>
    Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
    ae8ff9c5
r8a77990-ebisu.dts 1.48 KB