Re: [RFC PATCH 0/8] xilinx: tsn: Add TSN Endpoint Ethernet MAC driver support

Hi Andrew,

On 2/20/2026 7:06 PM, Andrew Lunn wrote:

On Fri, Feb 20, 2026 at 12:59:16PM +0000, Neeli, Srinivas wrote:

quoted

[AMD Official Use Only - AMD Internal Distribution Only]

Sorry, i'm not part of AMD...

quoted

quoted

So how does the host send a frame out Port 2? Is there an extra header
on the frame sent by EndPoint, which the switch interprets?

In this RFC, I configured all switch ports in forward mode. As a
result, when a frame is sent from the internal endpoint, it is
flooded to both external ports.  To forward packets to a specific
port instead of flooding, either static switch CAM entries need to
be configured or address learning should be enabled so the switch
can learn CAM entries dynamically.

Despite not being part of AMD, this part is important.

I don't care about how the RFC works, i want to know how the hardware
works, to ensure you have the correct choice of DSA vs pure switchdev.

Take the example of running Spanning Tree Protocol. The bridge needs
to send the BPDU out a specific port. What mechanism is used to do
that? It also needs to know which port a BPDU ingressed.

	Andrew

Hi Andrew,

I would like to briefly share an overview of our TSN switch capabilities 
and seek your guidance on the most appropriate Linux framework for the 
driver implementation specifically whether switchdev or DSA would be the 
better fit.

TSN Switch Capabilities
-----------------------
Our TSN subsystem supports the following IEEE TSN clauses:

IEEE 802.1Qbv – Time-Aware Shaper (scheduled traffic using gate control)
IEEE 802.1Qbu / IEEE 802.3br – Frame preemption
IEEE 802.1Qci – Per-Stream Filtering and Policing (PSFP), including: 
SDU-based filtering and Meter-based policing
IEEE 802.1CB – Frame Replication and Elimination for Reliability (FRER)
IEEE 802.1AS / IEEE 1588 – Time synchronization (PTP / gPTP)

Hardware Architecture Overview
------------------------------
The switch consists of three ports:

Port 0: Connected to the CPU (control/endpoint port)
Port 1: Connected to MAC1
Port 2: Connected to MAC2

MAC1 and MAC2 are capable of transmitting and receiving PTP packets, 
with received packets stored in internal BRAM. They will not be 
forwarded by switch to the internal endpoint (EP) and MAC network 
drivers xmit's and receives the PTP frames.
The switch forwards frames based on VLAN port membership and the CAM 
entries and switch supports TSN features such as CBS, Qci (PSFP) and 
802.1CB (FRER) through hardware configuration.
The CPU is intended to operate purely in the control plane and is not 
part of the forwarding data path.

Thank you very much for your time and guidance. Please let us know if 
any additional details would be helpful.


Best regards,
Neeli Srinivas