On 20/06/2024 10:48, Matthias Schiffer wrote: > On Thu, 2024-06-20 at 10:29 +0200, Krzysztof Kozlowski wrote: >> >> >> On 20/06/2024 10:26, Matthias Schiffer wrote: >>> On Thu, 2024-06-20 at 09:24 +0200, Krzysztof Kozlowski wrote: >>>> On 19/06/2024 13:24, Matthias Schiffer wrote: >>>>> While the current Device Trees for TI EVMs configure the PRUSS Ethernet >>>>> controller as a toplevel node with names like "icssg1-eth", allowing to >>>>> make it a subnode of the ICSSG has a number of advantages: >>>> >>>> What is ICSSG? The sram or ti,prus from the ethernet schema? >>> >>> ICSSG (Industrial Communication Subsystem (Group?)) is the main device described by the >>> ti,pruss.yaml binding (ICSS and PRUSS are different variants of similar IP cores); it is the >>> container for the individual PRU, TXPRU and RTU cores which are referenced by the ti,prus >>> node of the Ethernet schema. >>> >>> The entirety of PRU, TXPRU and RTU cores of one ICSSG, each with its own firmware, forms one >>> Ethernet controller, which is not quite a hardware device, but also not a fully virtual software >>> device. >> >> So it is not really child of ICSSG. >> >>> >>> The Ethernet controller only exists through the various ICSS subcores, so it doesn't have an MMIO >>> address of its own. As described, the existing Device Trees define it as a toplevel non-MMIO node; >>> we propose to allow it as a non-MMIO child node of the ICSSG container instead. >>> >>> If you consider moving the ethernet node into the ICSSG node a bad approach, we will drop this patch >>> and try to find a different solution to our issue (the Ethernet device staying in deferred state >>> forever when the ICSSG node is disabled on Linux). >> >> Just disable the ethernet. That's the expected behavior, I don't get >> what is the problem here. > > If the disabling happens as a fixup in the bootloader, it needs to know the name of the Ethernet > controller node (or iterate through the DTB to find references to the disabled ICSSG node). Which is already solved for several such cases, including ethernet devices? Aliases? > > The name is currently not used for anything, and not specified in the binding doc; the example uses > "ethernet", which is too unspecific, as there can be multiple ICSSG/PRUs, with each running a > separate Ethernet controller. Use existing solutions - aliases. > > Existing Device trees use "icssgX-eth" for an Ethernet controller running on the ICSSG with label > "&icssgX", but labels are a source concept and don't exist in the compiled DTB by default. > > I do have an idea for an alternative approach that does not need changes to the DT bindings: The PRU > Ethernet driver could detect that the referenced ti,prus are disabled and not just waiting to be > probed and then fail with ENODEV instead of EPROBE_DEFER. Sorry, but re-shuffling nodes into incorrect hardware description is not the workaround for your problem. Best regards, Krzysztof
