On Thu, Sep 29, 2022 at 12:22:15PM +0000, Yoshihiro Shimoda wrote: > Hi Andrew, > > > From: Andrew Lunn, Sent: Wednesday, September 28, 2022 9:01 PM > > > > > > How do you direct a frame from the > > > > CPU out a specific user port? Via the DMA ring you place it into, or > > > > do you need a tag on the frame to indicate its egress port? > > > > > > Via the DMA ring. > > > > Are there bits in the ring descriptor which indicate the user port? > > Can you set these bits to some other value which causes the switch to > > use its MAC table to determine the egress interface? > > I'm sorry, I misunderstood the hardware behaviors. > > 1) From CPU to user port: CPU sends a frame to all user ports. > 2) From user port to CPU: each user port sends a frame to each DMA ring. > > About the 1) above, the switch can have MAC tables and sends a frame to > a specific user port. However, the driver doesn't support it. In order to make STP and PTP work, you need to be able to send a frame out a specific port. With STP, that port can also be blocked, i.e. normal frames are not allowed to be transmitted/received, but these STP frames are allowed. You also need to know what port an STP frame was received on. So the switch probably has a mechanism to send a frame from the CPU out one specific port. And frames received from a user port and passed to the CPU should also be identifiable. There are different ways of doing this. DSA typically has an extra header on the frame, indicating where it is from/to. Some switches have extra bits in the DMA buffer descriptor indicating the port. > However, if I dropped specific registers setting, it doesn't work correctly. > I'll investigate why removing speeds of PHY didn't work. It could be the PHY is using SGMII, but your MAC needs 1000BaseX? Andrew
