[ibis-serdes-backchan] Re: [ibis-macro] Structural changes to the AMI standard required to support Backchannle Co-optimization
- From: Mike LaBonte <milabont@xxxxxxxxx>
- To: <ibis-serdes-backchan@xxxxxxxxxxxxx>
- Date: Fri, 11 Feb 2011 15:29:45 -0500
Hi Kumar,
I took the liberty of subscribing you to ibis-serdes-backchan. I also
authorized the email you sent before subscribing, which is why it went out
twice.
Mike
On 2/11/11 1:41 PM, "ckumar" <ckumar@xxxxxxxxxxx> wrote:
> I see that this proposal exposes the entire architecture of tx and rx to
> each other and expects them to interpret each other's parameters.
>
> The back channel communication standards are based on minimalist and
> necessary communication between rx and tx.
>
> from rx:
>
> 1. rx knows the number of taps in tx
> 2. rx can only ask tx to increment/decrement the taps. It does not or care
> to know what the absolute value of tx means
>
> from tx:
>
> tx communicates to rx whether the the specified taps are adjustable at all
> or they have reached their min/max limit
>
> The mode of communication also depends upon the standard and should be
> defined in the particular standards file
>
>
>
> On Fri, 11 Feb 2011 09:00:05 -0500, "Walter Katz" <wkatz@xxxxxxxxxx>
> wrote:
>> > IBIS-ATM,
>> >
>> >
>> >
>> > This e-mail is being sent to the IBIS ATM (Advanced Technology Modeling)
>> > group to describe the structural changes required to the IBIS-AMI
>> > interface.
>> > The Backchannel Reflector is being cc's as well.
>> >
>> >
>> >
>> > Two changes are required to the IBIS-AMI interface to support
> backchannel.
>> > The first is to allow the Tx AMI DLL to know what the Rx AMI DLL is
> telling
>> > it and the Rx AMI DLL needs to know what the Tx AMI DLL is telling it.
>> > Information is currently passed into a DLL as a text string in in a
> similar
>> > parameter tree format as defined in the .ami file for that model. The
> roor
>> > of this parameter tree is the root of the parameter tree in the .ami
> file.
>> > The simple enhancement to the AMI interface is to allow this string to
>> > contain two parameter trees, one with the root of the parameter tree for
>> > the
>> > model, and the other tree containing the root of the parameter tree fo
> the
>> > model at the other end of the channel. The following example should make
>> > this clearer:
>> >
>> >
>> >
>> > Assume that the parameter tree for the Tx model is:
>> >
>> >
>> >
>> > (Tx_Root (FFE_Tap (-1 -.03) (0 .9) (1 -.07)))
>> >
>> >
>> >
>> > and the parameter tree for the Rx model is:
>> >
>> >
>> >
>> > (Rx_Root (DFE_Tap (1 -.1) (2 -.05) (3 .05) (4 .1) (5 -.01)))
>> >
>> >
>> >
>> > In the current standard the Tx just gets the (Tx_Root .) tree and the Rx
>> > just gets the (Rx_Root .) tree.
>> >
>> >
>> >
>> > The proposed change will allow the Tx model to receive:
>> >
>> >
>> >
>> > (Tx_Root (FFE_Tap (-1 -.03) (0 .9) (1 -.07))) (Rx_Root (DFE_Tap (1 -.1)
> (2
>> > -.05) (3 .05) (4 .1) (5 -.01)))
>> >
>> >
>> >
>> > and the Rx model to receive
>> >
>> >
>> >
>> > (Rx_Root (DFE_Tap (1 -.1) (2 -.05) (3 .05) (4 .1) (5 -.01))) (Tx_Root
>> > (FFE_Tap (-1 -.03) (0 .9) (1 -.07)))
>> >
>> >
>> >
>> >
>> >
>> > Thus, the Rx model can determine the number of Tx pre-cursor and
>> > post-cursor
>> > taps, and the values of all of the Tx taps.
>> >
>> >
>> >
>> >
>> >
>> > The DLL's not only receive data in this format, but also output data in
>> > this
>> > same format. Thus the Rx model can output these same trees with updated
>> > values of the Tx Taps.
>> >
>> >
>> >
>> >
>> >
>> > As described in previous e-mails, there are three entry points to an AMI
>> > model, AMI_Init, AMI_GetWave, and AMI_Close. The AMI_Init entry has a
>> > parameters_in pointer and a parameters_out pointer. The AMI_GetWave
> entry
>> > only has a parameters_out pointer. Since Backchannel will require the
>> > ability to pass a parameter tree inot the AMI_GetWave entry, the AMI
>> > interface standard needs to modified to allow the AMI_GetWave
>> > parameters_out
>> > pointer to also serve as a pointer to an input string.
>> >
>> >
>> >
>> > To enable the above changes, we will need to define a new Reserved
>> > Parameter
>> > to indicate that this DLL does support multiple parameter trees in the
>> > input
>> > parameter tree, and that the AMI_GetWave support the parameter_out
> pointer
>> > use as an input as well as an output.
>> >
>> >
>> >
>> > Walter
>> >
>> >
>> >
>> >
>> >
>> > Walter Katz
>> >
>> > Chief Scientist
>> >
>> > Signal Integrity Software, Inc.
>> >
>> > wkatz@xxxxxxxxxx
>> >
>> > 303.449-2308
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