I'm looking for clarification on what actually needs to happen in order for a device to support PCIe bifurcation. Some forums say it's motherboard dependent, making me think it's not tied to the processor I choose, but all that is in the realm of PC hardware. My application is on an single board computer (SBC). To clarify, my application is splitting the x4 PCIe 2.1 Lanes from a RK3399 into 2 x2 lanes for 2 SATA adapters. As far as I'm aware, bifurcation is what I want, but even that I'm not completely sure of. Sorry if this is too broad, but nowhere online can I find the information I'm looking for.
Electronic – Requirements for PCIe Bifurcation on SBC
pcie
Best Answer
It’s entirely dependent on the root complex and its capabilities. Bifurcation is a fairly recent development only showing up in non-server x86 motherboards about 1-1/2 years ago (e.g., Intel x299 / AMD x399.) Server motherboards have supported it a bit longer using switches.
Not only that, even if the hardware supports it, the BIOS needs to support it, too.
So it’s a question for Rockchip. My guess is the RK3399 does not support it. (Followup: it doesn't.)
That said, if you’re just doing SATA then you don’t really need bifurcation, the PCIe-SATA bridge takes can take care of that (4-port PCIe - SATA adapters are common and cheap.) You would only need to bifurcate if you wanted direct tie to PCIe / NVMe. Or maybe I’m misunderstanding your question?