Hello eli,
thank you for your fast response, and sorry for my delay.
If and which motherboards connect this bus to some controller is also a question.
All modern chipsets include one or more SMBus-Host-Controllers so it is very likely that the most motherboards has this 2 lines on their PCB. The Linux-Kernel does support all of the currently used SMBus-Host-Controllers, the needed infrastructure is available but the documentation say it is not frequently used and so not well tested. (it seems the SMBus-Infrastructure of Linux is mostly used for plain I²C and some
private use cases)
My question comes from an other direction, i must develop a kind of mainboard with 2 or 3 PCI-Express-Slots and now is my question: "how likely is the SMBus used with add-in cards and for what functionality?" that means "what is the potential benefit of supporting the SMBus?". The Slots should be DC-isolated from the mainboard and this makes the implementation of SMBus very complicated.
The answer that i will prefer is "SMBus is obsolete for today PCI(e) add-in cards, the 2 pins can be unconnected without the risk of loosing any relevant/pertinent feature." but if exist a real benefit (with commonly used add-in cards) by supporting the SMBus then it can be a real reason for paying the additional costs for this feature.
Maybe others have more experience with this.
I hope that, too. Additional answers are very welcome.
The decision must not be taken in the next few days.
Regards,
Erik