Hi Mika, 2018-01-18 14:00 GMT+01:00 Andrew Lunn <andrew@xxxxxxx>: >> I CC'ed Mika since he is more familiar with handling these bits of ACPI >> specs - I wonder whether this is a problem that cropped up on x86 >> systems too. > > Hi Lorenzo > > There is nothing about MDIO, PHYs, Ethernet switches, etc in version > 6.2 of the spec. If x86 has this, it must be after 6.2 was released. > I would not be too surprised if x86 has none of this. If you look at > the typical drives used on x86, i210, e1000e, ixgb, r8169, etc. They > are all PCI devices, and hide all this. > >> I do not think there is one and only answer but there must be a single >> set of bindings and if the ACPI specs already cater for some of them >> we have to reuse them. > > Agreed. Due diligence so far suggests there is nothing already > defined. But im a newbie to ACPI, so could be looking in the wrong > place. I really hope there is somebody like Rob Herring, the DT > maintainer, who keeps an eye on all ACPI talk and would tell us if we > are heading off in the wrong direction. > My initial approach with MDIO bus with PHYs as child nodes was super easy to describe and handle in Linux - please refer to: - typical representation of mdio bus with the phys - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/net/mdio.txt?h=v4.15-rc8 - my patches in the initial series However I guess it would be more proper to use the GenericSerialBus-based description, as advised in ACPI Spec. The question is, whether we should define new type of a bus or not (MdioSerialBus, similar to e.g. I2cSerialBus). Since I have a code that can be tested and easily modified to use different ACPI approaches with real platform MDIO controller (mvmdio.c) and NIC (mvpp2.c), in coming weeks I may be able to find some time to prepare a proof of concept based on GenericSerialBus. Please expect some RFC patches hopefully right after the coming merge window is closed. Of course, if I come up on some ACPI - specific implementation questions, I won't hesitate to ask in this thred. I will also appreciate any hints. For now my two main concerns are: - The PHY address on the mdio bus - should it be put into _CRS -> GenericSerialBus() field or separate _ADR? I'd lean towards first option. - The PHY type - in Linux it's resolved basing on two generic compatible strings (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/net/phy.txt?h=v4.15-rc8). I'd put it as a sort of ID into GenericSerialBus(). If you agree - any specific filed that you would try to use? Do I understand correctly that the MDIO controller node should comprise OperationRegion() definition of the GenericSerialBus? I'm looking forward to your feedback. Thanks, Marcin -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
