Re: [RFC PATCH] net: macb: Add gmii2rgmii converter support

[Florian Fainelli]

On June 19, 2016 10:27:17 PM MST, Kedareswara rao Appana <appana.durga.rao@xxxxxxxxxx> wrote:
>This patch adds support for gmii2rgmii converter
>in the macb driver.
>
>The GMII to RGMII IP core provides the
>Reduced Gigabit Media Independent Interface
>(RGMII) between Ethernet physical media devices
>And the Gigabit Ethernet controller.
>This core can switch dynamically between the
>Three different speed modes of operation (10/100/1000 Mb/s).
>MDIO interface is used to set operating speed of Ethernet MAC.
>
>Signed-off-by: Kedareswara rao Appana <appanad@xxxxxxxxxx>
>---
>--> Tried to include this Coverter support in the
>PHY layer but it won't fit into the PHY framework as the
>coverter won't have vaild vendor/Device id registers.
>--> The Converter has only one register (16) that need's
>to be programmed with the external phy negotiated speed.
>--> The converter won't follow the Standard MII(ieee 802.3 clause 22).
>--> Will appreciate if someone can help on adding this coverter support

With the fixed PHY emulated PHY and registering a link_update callback (see drivers/net/dsa/bcm_sf2.c for an example), you could read specific registers which indicates link parameters and update the PHY device with these. 

How exactly is this converter working?

-- 
Florian