66e69d8849
Starting with:
bcf3440c6dd7 ("net: phy: micrel: add phy-mode support for the KSZ9031 PHY")
the micrel phy driver started respecting phy-mode for the KSZ9031 PHY.
At least with kernel v5.8 configuration provided by this fixup was
overwritten by the micrel driver.
This fixup was providing following configuration:
RX path: 2.58ns delay
rx -0.42 (left shift) + rx_clk +0.96ns (right shift) =
1,38 + 1,2 internal RX delay = 2.58ns
TX path: 0.96ns delay
tx (no delay) + tx_clk 0.96ns (right shift) = 0.96ns
This configuration is outside of the recommended RGMII clock skew delays
and about in the middle of: rgmii-idrx and rgmii-id
Since most embedded systems do not have enough place to introduce
significant clock skew, rgmii-id is the way to go.
In case this patch breaks network functionality on your system, build
kernel with enabled MICREL_PHY. If it is still not working then try
following device tree options:
1. Set (or change) phy-mode in DT to:
phy-mode = "rgmii-id";
This actives internal delay for both RX and TX.
1. Set (or change) phy-mode in DT to:
phy-mode = "rgmii-idrx";
This actives internal delay for RX only.
3. Use following DT properties:
phy-mode = "rgmii";
txen-skew-psec = <0>;
rxdv-skew-psec = <0>;
rxd0-skew-psec = <0>;
rxd1-skew-psec = <0>;
rxd2-skew-psec = <0>;
rxd3-skew-psec = <0>;
rxc-skew-psec = <1860>;
txc-skew-psec = <1860>;
This activates the internal delays for RX and TX, with the value as
the fixup that is removed in this patch.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.