On Thu, Feb 03, 2022 at 10:34:25AM +0100, Oliver Neukum wrote: > > On 27.01.22 11:57, Greg KH wrote: > > On Thu, Jan 27, 2022 at 11:49:01AM +0100, Oleksij Rempel wrote: > >> Add devicetree label property for usbnet devices and related yaml > >> schema. > > That says _what_ you are doing, but not _why_ you would want to do such > > a crazy thing, nor what problem you are attempting to solve here. > > could you at least describe what kind of systems we are talking > about? Is this for a limited set of embedded devices? > Are we talking about devices embedded on a motherboard, > which happen to be connected by USB? In this particular use case there is a PCB with a imx6 SoC with hard wired USB attached USB-Ethernet-MAC adapters. One of these adapters is connected in the same PCB to an Ethernet switch chip. There is a DSA driver for the switch, so we want to describe the whole boards in a DT. Putting a label in the DT that renames the network interface is "nice to have" but not so important. As the DT DSA bindings rely on linking a MAC phandle to the switch we need to describe the USB Ethernet adapter in the DT, this is more important. See this discussion: https://lore.kernel.org/all/20220127120039.GE9150@xxxxxxxxxxxxxx/ > That is, are we talking about another kind of firmware > we are to take information about devices from? There is no other firmware involved. The switch chip is attached via RGMII to the USB/MAC and with SPI to the CPU for the configuration interface. (I2C to the CPU or MDIO to the USB/MAC would be another option for the configuration interface.) > And if so, why are you proposing to solve this on the > USB driver level? > It looks to me like those devices are addressed by > their USB path. But still there is no reason that a USB > driver should actively interpret firmware stuff that > comes from a source that tells us nothing about USB > properties. > In other words it looks to me like you are trying to put > a generic facility for getting device properties into > a specific driver. The question whether device names > should be read out of firmware is not a USB question. > > I would suggest you implement a generic facility > in the network layer and if everybody is happy with that > obviously usbnet can pass through a pointer for that > to operate on. Frankly, it looks to me like you are > implementing only a subset of what device tree > could contain for your specific use case. Sounds good, but we'll focus on the DSA use case, as this is more important. So patches 1 and 2 of this patches set have highest prio for us. Regards, Oleksij & Marc -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
