Can FPE(IEEE802.1Qbu) work with TBS(Time-Based Scheduling) on GMAC0 of S32G274

[sarh2o]

Hi NXP experts,

I'm working on enabling FPE (IEEE802.1Qbu) on GMAC0 of S32G274 for VxWorks.

The specific board which I'm using is S32G274-EVB.

I'm referring to document "GMAC Subsystem RM(GMACSUBSYSRM)".

In chapter 1.9.13 Frame Preemption (FPE), at the end of page 726,I saw a note:

"Frame scheduling (EST) and frame preemption (FPE) cannot be used at the same time."

But the following chapter "1.9.13.1 GCL Modification to Support FPE" is just talking about how to make EST work with FPE.

It is confusing.

When I tried to find any descriptions about how to make TBS work with FPE, I found nothing.

I also checked the linux driver provided by NXP. I only saw that FPE was configured with EST but didn't see that FPE was configured with TBS.

So I'd like to confirm with you whether FPE can work with TBS?

I guess that maybe the "note" I mentioned above is going to say that:

"TBS and FPE can't be used at the same time"

Could you please help to clarify?

Thanks!

[sarh2o]

Hi @Bio_TICFSL and NXP experts,

I still have some questions about topic.

Please see my last post.

Could you please help to answer?

Thanks!

[sarh2o]

Hi @Bio_TICFSL ,

Great thanks for your confirmation! That's very helpful!

Since I'm using S32G274. I cannot configure FPE with EST, right?

Is there any limitation about configuring TBS with FPE?

If TBS can work with FPE, I'd like to know more details about how to configure.

"GMAC Subsystem RM(GMACSUBSYSRM)" only describes how to configure EST with FPE.

But I'm working on G2, I can't use EST and FPE together.

I want to use TBS with FPE for TSN stream.

"GMAC Subsystem RM(GMACSUBSYSRM)" says that there is a "Set-and-Hold-MAC" operation which is used to cease preemptable traffics and there is a "Set-and-Release-MAC" operation which is used to resume preemptable traffics.

For EST, "Set-and-Hold-MAC" and "Set-and-Release-MAC" are controlled by TC0's bit of Gate Control of GCL.

If I use TBS instead of EST, should I still need to configure "Set-and-Hold-MAC" and "Set-and-Release-MAC"?

If so, how should I configure?

By the way, where can I see TKT0549123.

Thanks again!

[Bio_TICFSL]

Hello Sarh2o,

On S32G2 GMAC, Frame scheduling (EST) and frame preemption (FPE) cannot be used at the same time. This is a limitation in G2, which has been fixed on G3.
To give a brief on the issue, when there is data in MTL FIFO of both pre-emptable and express queue, pre-emptable does not send packets even if express queue gates are closed. More about the limitation has been covered in the TKT0549123.

Regards