Martin Blumenstingl e5f3a4a56c Documentation: devicetree: clarify usage of the RGMII phy-modes ... RGMII requires special RX and/or TX delays depending on the actual hardware circuit/wiring. These delays can be added by the MAC, the PHY or the designer of the circuit (the latter means that no delay has to be added by PHY or MAC). There are 4 RGMII phy-modes used describe where a delay should be applied: - rgmii: the RX and TX delays are either added by the MAC (where the exact delay is typically configurable, and can be turned off when no extra delay is needed) or not needed at all (because the hardware wiring adds the delay already). The PHY should neither add the RX nor TX delay in this case. - rgmii-rxid: configures the PHY to enable the RX delay. The MAC should not add the RX delay in this case. - rgmii-txid: configures the PHY to enable the TX delay. The MAC should not add the TX delay in this case. - rgmii-id: combines rgmii-rxid and rgmii-txid and thus configures the PHY to enable the RX and TX delays. The MAC should neither add the RX nor TX delay in this case. Document these cases in the ethernet.txt documentation to make it clear when to use each mode. If applied incorrectly one might end up with MAC and PHY both enabling for example the TX delay, which breaks ethernet TX traffic on 1000Mbit/s links. Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2016-11-28 12:06:54 -05:00
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bindings	Documentation: devicetree: clarify usage of the RGMII phy-modes	2016-11-28 12:06:54 -05:00
00-INDEX
booting-without-of.txt
changesets.txt	Documentation: devicetree: changesets do locking on their own meanwhile	2016-08-30 17:07:44 -05:00
dynamic-resolution-notes.txt
of_unittest.txt
overlay-notes.txt
todo.txt
usage-model.txt