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AHB Bufferable/Non-bufferable write

Hariprem Arora
Note: This was originally posted on 12th September 2008 at http://forums.arm.com

Hi,

Please clarify the following issue related to AHB write:

If HPROT[2] = 1, AHB write is bufferable and we need to provide OKAY response as soon as the AHB slave interface receives data without caring that the data is actually written into the memory or not.

if HPROT[2] = 0, AHB write is non-bufferable, AHB slave interface needs to provide response to the master only when the data is actually written into the memory.

The issue is that if we see this non-bufferable transaction, the state of HRESP will by default be OKAY (HREADY is HIGH to accept the next data) and it means that we are providing the response in advance for non-bufferable write.

Please clarify how to distinguish between the two transactions.
If possible, please provide waveforms for INCR undefined length & non-bufferable write
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    Note: This was originally posted on 15th September 2008 at http://forums.arm.com

    Hi JD,

    Thanks for clarification regarding response from AHB slave for non-bufferable write.

    so from the explanation, I understood that AHB slave has to pull HREADY LOW to insert wait state.

    Does it mean AHB slave can insert wait state for each data transacted in a burst to give actual destination slave response. Is this feasible with regards to the throughput.

    Hari
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  • 0
    Note: This was originally posted on 15th September 2008 at http://forums.arm.com

    Hi JD,

    Thanks for clarification regarding response from AHB slave for non-bufferable write.

    so from the explanation, I understood that AHB slave has to pull HREADY LOW to insert wait state.

    Does it mean AHB slave can insert wait state for each data transacted in a burst to give actual destination slave response. Is this feasible with regards to the throughput.

    Hari
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