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    SubjectRe: [PATCH] ARM: mach-imx6q: add ksz9131rn_phy_fixup
    On Thu, Mar 05, 2020 at 03:38:05PM +0100, Oleksij Rempel wrote:
    > Hi Philippe,
    >
    > On Thu, Mar 05, 2020 at 02:49:28PM +0100, Philippe Schenker wrote:
    > > The MAC of the i.MX6 SoC is compliant with RGMII v1.3. The KSZ9131 PHY
    > > is like KSZ9031 adhering to RGMII v2.0 specification. This means the
    > > MAC should provide a delay to the TXC line. Because the i.MX6 MAC does
    > > not provide this delay this has to be done in the PHY.
    > >
    > > This patch adds by default ~1.6ns delay to the TXC line. This should
    > > be good for all boards that have the RGMII signals routed with the
    > > same length.
    > >
    > > The KSZ9131 has relatively high tolerances on skew registers from
    > > MMD 2.4 to MMD 2.8. Therefore the new DLL-based delay of 2ns is used
    > > and then as little as possibly subtracted from that so we get more
    > > accurate delay. This is actually needed because the i.MX6 SoC has
    > > an asynchron skew on TXC from -100ps to 900ps, to get all RGMII
    > > values within spec.
    >
    > This configuration has nothing to do in mach-imx/* It belongs to the
    > board devicetree. Please see DT binding documentation for needed
    > properties:
    > Documentation/devicetree/bindings/net/micrel-ksz90x1.txt

    It probably does not even need that. Just

    phy-mode = <rgmii-txid>

    Also, please Cc: netdev for network code.

    Andrew

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