135e30180f
Some boards do not have the RX_ER MII signal connected. Normally in such situation, those pins would be grounded, but then again, some boards left it electrically floating. When sending traffic to those switch ports, one can see that the N_SOFERR statistics counter is incrementing once per each packet. The user manual states for this counter that it may count the number of frames "that have the MII error input being asserted prior to or up to the SOF delimiter byte". So the switch MAC is sampling an electrically floating signal, and preventing proper traffic reception because of that. As a workaround, enable the internal weak pull-downs on the input pads for the MII control signals. This way, a floating signal would be internally tied to ground. The logic levels of signals which _are_ externally driven should not be bothered by this 40-50 KOhm internal resistor. So it is not an issue to enable the internal pull-down unconditionally, irrespective of PHY interface type (MII, RMII, RGMII, SGMII) and of board layout. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.