On 8/4/26 7:41 AM, Akash Nair wrote:
Hi,
sorry for the late reply, I am buried in emails.
+CC Alice, Peng, Simon, since they might have something to say here.
I am currently working on Ethernet driver integration for Synopsys IP in
U-Boot, specifically focusing on the Synopsys XPCS (Physical Coding Sublayer)
block.
After reviewing the current codebase, I noticed that while Linux has a
dedicated XPCS subsystem driver (drivers/net/pcs/pcs-xpcs.c), U-Boot does not
currently have a standalone equivalent.
Before starting development on a standalone driver, I would appreciate your
guidance on a few architectural questions:
1. Existing References:
Is there any existing/in-flight work or reference implementation in U-Boot
or vendor trees for Synopsys XPCS handling?
2. APB3 Indirect Access vs. Clause 45 MDIO:
Most typical implementations access the XPCS registers over MDIO Clause 45.
In our hardware architecture, the XPCS is accessed via an indirect access
mechanism using an APB3 management interface instead of MDIO. Are there any
existing driver patterns or abstractions in U-Boot handling XPCS/PCS over
non-MDIO register buses?
3. Design Context:
Is the lack of a dedicated XPCS driver in U-Boot primarily due to design
preference (e.g., relying on TF-A/BootROM pre-configuration, or embedding
initialization into SoC glue code), or simply that a generic driver model port
has not yet been submitted?
The later, nobody implemented the XPCS yet.
4. Upstream Integration & Guidelines:
Is there interest in upstreaming a standalone Synopsys XPCS driver? If we
implement this driver under U-Boot's Driver Model (DM), what key requirements
or design points should we keep in mind to ensure it aligns with current
networking uclass standards?
Any insights, historical context, or recommendations on how best to approach
this within U-Boot would be greatly appreciated.
--
Best regards,
Marek Vasut
