On 11/29/2020 3:04 PM, Andrew Lunn wrote: > On Sun, Nov 29, 2020 at 11:51:43PM +0100, Adrien Grassein wrote: >> Hi Andrew, >> >> Please find my answers below. >> >> Le dim. 29 nov. 2020 à 23:41, Andrew Lunn <andrew@xxxxxxx> a écrit : >> >> On Sun, Nov 29, 2020 at 10:59:58PM +0100, Adrien Grassein wrote: >> > Add dt-bindings explanation for the two new gpios >> > (mdio and mdc) used for bitbanging. >> >> Hi Adrien >> >> What is missing is an explanation of why! >> >> I'm sorry, it's my first upstreaming attempt. > > Hi Adrien > > Please take a look at > > https://www.kernel.org/doc/html/latest/networking/netdev-FAQ.html > > It is normal to have a patch 0/X which explains the big picture. > > Then the commit message for each patch should explain why you are > doing something. That is much more important than what you are doing, > i can see that from the patch itself. > >> I am currently upstreaming the "Nitrogen 8m Mini board" that seems to not use a >> "normal" mdio bus but a "bitbanged" one with the fsl fec driver. > > Any idea why? > > Anyway, you should not replicate code, don't copy bitbanging code into > the FEC. Just use the existing bit-banger MDIO bus master driver. Right there should be no need for you to modify the FEC driver at all, there is an existing generic bitbanged MDIO bus driver here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/mdio/mdio-gpio.c with its binding here: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/net/mdio-gpio.txt so all you should need to do is make sure that you place a "virtual,mdio-gpio" node, declare the PHY devices that are present on that bus, and have your FEC nodes point to those PHY devices with an appropriate 'phy-handle' property. -- Florian
