IBIS Macromodel Task Group

Meeting date: 16 September 2014

Members (asterisk for those attending):
Altera:                     * David Banas
ANSYS:                      * Dan Dvorscak
                            * Curtis Clark
Avago (LSI)                   Xingdong Dai
Cadence Design Systems:     * Ambrish Varma
                              Brad Brim
                            * Kumar Keshavan
                              Ken Willis
Ericsson:                     Anders Ekholm
Intel:                        Michael Mirmak
Keysight Technologies:        Fangyi Rao
                            * Radek Biernacki
Maxim Integrated Products:    Hassan Rafat
Mentor Graphics:            * John Angulo
                            * Arpad Muranyi
Micron Technology:          * Randy Wolff
                              Justin Butterfield
QLogic Corp.                  James Zhou
                              Andy Joy
eASIC                         Marc Kowalski
SiSoft:                       Walter Katz
                            * Todd Westerhoff
                            * Mike LaBonte
Synopsys                      Rita Horner
Teraspeed Consulting Group:   Scott McMorrow
                            * Bob Ross

(Note: Agilent has changed to Keysight)

The meeting was led by Arpad Muranyi.

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Opens:

- None

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Call for patent disclosure:

- None

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Review of ARs:

- Bob: Send BIRD 147 comments to Ambrish
  - Done

- Ambrish - Investigate other ways to communicate tap coefficients in BIRD 147.
  - In progress.
  - Todd asked for the new version to be posted.

- Arpad to review IBIS spec for min max issues.
  - In progress.


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New Discussion:


BIRD 128:

- Radek: This is needed for BIRD 147 but is otherwise independent.
  - The usage details are not spelled out enough to avoid inconsistencies.
  - Walter had agreed to that.
  - Walter, Ambrish and Radek should meet to work it out.
  - No specific required changes are known yet.
- Arpad: We can table this until there is an update.
- Todd: RX ami_parameters_out would be used to feed data to TX ami_parameters_out in Init.
  - BIRD 128 does not support any parameter passing in Init.
- Ambrish: That is already handled in IBIS.
- Todd: It does not support using into ami_parameters_out as an input, but this BIRD calls for that.
- Ambrish: That needs to be addressed.
- Radek and Arpad agreed.
- Bob: It could be voted if updated by this Friday, but we might not want to push that hard.


BIRD 147:

- Ambrish showed BIRD 147 draft 13.
- Bob: Numerical training modes were moved into the BIRD text, they are important.
  - There were no definitions of coefficients, that was addressed.
  - The in/out changes we discussed are needed too.
- Ambrish: I will change that and send it to Mike.
- Ambrish: Will this also be submitted to the open forum?
- Radek: Points from the last meeting have not been addressed yet.
  - Walter expressed strong opinions by email after the meeting.
  - It might bounce back to us anyway if submitted.
- Arpad: There will be no other BIRD changes, it is ready.
- Ambrish: The new discussions are more philosophical.
- Arpad: We need to decide what recommendation to make to the open forum.
- Todd: We have talked with semiconductor vendors about their requirements.
  - This is not done yet.
  - Backchannel training modeling is very important to them.
  - Not having to do that is equally important for performance reasons.
  - It can be done quickly in Init without calling GetWave.
  - They have algorithms to do it.
  - They expect customers to skip GetWave most of the time.
  - They are concerned that the BCI file will constrain TX to RX data passing.
  - The allowed BCI keywords might constrain them.
  - It's hard to tell what is allowed.
  - The Init and GetWave training descriptions are loose.
- Ambrish: When the TX thinks the RX can't take any more settings it sends a range.
- Todd: The messaging has two types of values.
  - The vendor needs to address things like granularity.
- Ambrish: That is in the Protocol_Specific section.
- Todd: The RX has to generate tap coefficients with some granularity.
- Ambrish: The TX sends its allowable tap values.
- Todd: We had not heard it could be done this way.
  - This is based on the AMI syntax because we know it.
  - The AMI file sets possible values for parameters, just a leaf and values.
  - In Init mode tap has min/max but in GetWave it has mode/adjustment.
  - This is the only place where behavior would change.
- Bob: This is a bit uncomfortable.
- Ambrish: It has to be understood that if there are two values they are min and max.
- Todd: Page 6 says the BCI file sets the range but the model can go beyond.
- Ambrish: It could modify less taps or more taps than specified.
- Todd: Do we spell out that an RX must ignore anything it doesn't understand?
- Ambrish: That should be understood. The RX may ignore or accept.
- Todd: It says a model can support more than the BCI has yet still point to the BCI.
  - The TX will send taps info the RX might know nothing about.
- Ambrish: There is no confusion because with type tap it is known that 0 is the main tap.
- Todd: Models today are expected to ignore parameters they don't understand.

AR: Ambrish send updated BIRD 147 draft to Mike for posting.

- Arpad: We still need to decide our recommendation to the open forum.
- Radek: We still need to settle some issues.
  - Ambrish needs to clarify some things.
  - The TX and RX know some things about each other.
- Ambrish: They might not know if the other supports GetWave for example.
- Radek: This puts information where it doesn't need to be.
- Arpad: Walter's flow related questions are not addressed in this BIRD.
  - It has a specific order of events.
  - We need to decide if this BIRD is sufficient.
  - It might be rejected.
- Ambrish: That will add much complication for something that may not be required.
  - We should wait for someone to say it is needed instead of speculating.
- Arpad: We should not put limits in front of us.
- Radek: Do we pass this and start a new BIRD?
- Arpad: Either that or we say this BIRD is not sufficient.
- Todd: We should take a meeting or two to decide what the requirements are.
  - Only then should we look at if this BIRD meets it.
- Ambrish: That would be going back to the start.
  - We have already had discussions about requirements.
- Arpad: We could pull those slides and look at it next week.
- Todd: That would be good.
- Ambrish: Does the BIRD meet your expectations or not?
- Todd: Possibly but we need to look at it.
  - Much editorial improvement is possible.
- Arpad: We should not do that.
- Todd: If it passes there is room for ambiguity.
- Ambrish: Walter felt this BIRD needed no changes.
  - Todd and Walter should coordinate on this.

AR: Todd produce slides for co-optimization requirements discussion next week.

- Ambrish: I would like to see Todd's BIRD 147 notes.

AR: Todd send BIRD 147 notes to Ambrish.

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IBIS Interconnect SPICE Wish List:

1) Simulator directives
