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axi ordering

Hi 
 the master is connected  to axi-interconnect and  two slaves(A and B) are connected to axi-interconnect.
The master send a write transcation(AA)   to  slave A and then send  a write transcation(BB)   to slave B with same ID.
the two transcations with the same ID, axi mention that  the master should receive A1's response  and then B1's response from axi-interconnect..

Now,i have some question about that.
the two transcations must arrive to slave A and then arrive to slave B?
is it possible that  the transcations can arrive to two slaves  out of order and  axi-interconnect. send their response to master in order ?

thanks

Parents
  • Obviously if you are using the same ID, the master must issue all the WDATA for transaction AA before it send the first WDATA for transaction BB, so the only reason slave B might see WDATA before slave A would be if there was lots more registering on the path from the interconnect to slave B compared to registering on the path to slave A (the AA data will all have been sent by the interconnect before it can send any data to for BB).

    However even if slave A has received all the AA data before slave B sees any BB data, there could be a long delay before slave A returns the BRESP for AA, meaning slave B could return the BRESP for BB first. In that case the interconnect would need to stall the BB BRESP response until the AA BRESP has been received, so the master will always see the correctly ordered responses.

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  • Obviously if you are using the same ID, the master must issue all the WDATA for transaction AA before it send the first WDATA for transaction BB, so the only reason slave B might see WDATA before slave A would be if there was lots more registering on the path from the interconnect to slave B compared to registering on the path to slave A (the AA data will all have been sent by the interconnect before it can send any data to for BB).

    However even if slave A has received all the AA data before slave B sees any BB data, there could be a long delay before slave A returns the BRESP for AA, meaning slave B could return the BRESP for BB first. In that case the interconnect would need to stall the BB BRESP response until the AA BRESP has been received, so the master will always see the correctly ordered responses.

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