On Fri, 18 Jan 2019 15:35:35 +0100 Gregory CLEMENT <gregory.clement@xxxxxxxxxxx> wrote: > > The basic module can be extended by different modules. > > When those modules are connected, U-Boot has to let kernel know via > > device-tree. Since modules can be connected in different order and > > some modules can be connected multiple times (up to three 8-port > > switch modules can be connected), using dtb overlays would result in > > too files. > > What do you mean by too many files? > > The dtb overlays seems really matches your situation. > Usually we have one dtb part by module and then we mix them together. > > Gregory Hi Gregory, the problem is that in some cases here some even if you have the same module, some parameters have to be different depending on which position the module is in the topology and what type of module is before it. For example up to three switch modules can be connected one after another, and although physically they are the same, their dtb parameters (MDIO address and whether they are connected to CPU or another switch module) are different. So if I wanter to use overlays without dtb modification from u-boot, I would have to have three overlays for Peridot module, for topologies: peridot peridot-peridot peridot-peridot-peridot three for Topaz module: topaz peridot-topaz peridot-peridot-topaz and four for SFP module: sfp peridot-sfp peridot-peridot-sfp peridot-peridot-peridot-sfp For the PCIe and USB module this is not the case, only one overlay for each. But I thought (and still think) that in this case it is more elegant to just enable the modules in U-Boot than to use so many different overlays. And since I already thought up this solution for SFP and switch modules, I used it for the PCIe and USB modules as well, instead of mixing overlays there. I am of course willing to rewrite this to use overlays, if you guys are unwilling to merge it done this way, but I think this solution is better. Also, I would like to have the dts definitions for all modules officially supported by Mox to have in the kernel, and if this was done via overlays, it would not be merged, or am I wrong? Are there overlay dts sources for some device in the kernel? Marek
