[ibis-macro] Minutes from the 08 Apr 2014 ibis-atm meeting
- From: Mike LaBonte <mike@xxxxxxxxxxx>
- To: ibis-macro@xxxxxxxxxxxxx
- Date: Wed, 09 Apr 2014 18:53:24 -0400
Minutes from the 08 Apr 2014 ibis-atm meeting are attached.
Mike
IBIS Macromodel Task Group
Meeting date: 08 April 2014
Members (asterisk for those attending):
Agilent: * Fangyi Rao
* Radek Biernacki
Altera: * David Banas
ANSYS: * Dan Dvorscak
* Curtis Clark
Cadence Design Systems: * Ambrish Varma
Brad Brim
* Kumar Keshavan
* Ken Willis
Scott Huss
Ericsson: Anders Ekholm
Intel: Michael Mirmak
LSI Amaresh Malipatil
Dai Xingdong
Maxim Integrated Products: Hassan Rafat
Mentor Graphics: * John Angulo
* Arpad Muranyi
Andrey Matvienko
* Vladimir Dmitriev-Zdorov
Micron Technology: Randy Wolff
Justin Butterfield
QLogic Corp. James Zhou
Andy Joy
SiSoft: * Walter Katz
* Todd Westerhoff
* Mike LaBonte
Teraspeed Consulting Group: Scott McMorrow
* Bob Ross
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:
- Walter send presentation for posting
- Sent to reflector
- Ambrish send BIRD147 update for posting
- Sent draft 9 to reflector
- Mike post these
- Not done yet, will be done.
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New Discussion:
Backchannel:
- Arpad showed draft 9 of BIRD 147
- Ambrish described the changes.
- Training_Mode changes from Value to List Format.
- The document is in a more readable format.
- Arpad: Are there any IBIS spec portions that need to be declared as changed?
- Ambrish: This is all new.
- Todd: This is hard to read.
- It is missing an architectural overview.
- The BCI defines the structure of the passed messages, right?
- Ambrish: The BCI gives the minimum the models should support.
- The TX and RX may go beyond that.
- Todd: This is about standard protocols.
- It doesn't say that it emulates the protocol implement in hardware.
- It is defined in a way that invites confusion with AMI parameters.
- It infringes on AMI In/Out, which tells tools what to expect.
- That is now declared here, not in the AMI file.
- Does the Training_Done usage rule mean that it appears only in a BCI file?
- Ambrish: Yes.
- Ken: There was discussion about putting this in AMI, but we decided there
could be problems.
- Having the TX and RX point to the same BCI file insures they use the same
protocol.
- We put architectural information in slides some time ago, that could be
incorporated.
- Todd: The specification needs to be as clear as possible.
- Walter: There could be a cookbook for something as significant as this.
- Radek: The AMI_Init extension seems primitive.
- A new API would be better.
- Ambrish: It is only needed when we don't have AMI_GetWave.
- Kumar: Radek is asking for a separate API for training.
- This is a different architecture.
- Vladimir: This is about repeating what is done in time domain in statistical
mode.
- Why not reverse that?
AR: Todd provide BIRD 147 with annotated comments
- Walter showed a presentation "Backchannel Issues"
- slide 3:
- Walter: ASCII files includes .ami and .bci.
- These are what the user community would like to see.
- slide 4:
- Walter: Standards call for using multiple taps, with various minimums and
maximums.
- This applies to several standards.
- slide 5:
- Walter: The terms "register" and "index" are important here.
- There can be invalid settings combinations.
- We don't want register settings, but we do want to use indexes.
- Either indexes or coefficients are always exposed.
- With statistical coefficients must be used.
- slide 6:
- Walter: The system integrator must choose presets.
- Backchannel uses an associated link which needs BER < 1e-5.
- You have to start off with presets that achieve that.
- slide 7:
- Walter: We need certain AMI Reserved_Parameters.
- These are common to all training protocols.
- Fangyi: This is for RX to TX adjustment commands?
- Walter: Yes.
- Fangyi: Would this be in a protocol definition?
- Walter: This would be protocol-agnostic.
- At the end of TD optimization the TX can be closed and reopened to start
normal operation.
- We must tell AMI_Init and AMI_GetWave to convert indexes to coefficients.
- IC vendors need to supply a utility to convert to register values.
- The BCI file really belongs only to the RX.
- TX models are very generic.
- We might eliminate the BCI file altogether.
- I have draft text to put together a BIRD.
- It allows either Init or GetWave to handle training.
- Would like BIRD 147 to take this approach, or I will propose one.
- David: Why does the TX have to tell the tool it is optimizing taps?
- Also is there multiple entries into Init?
- Walter: It takes only one pass.
- Kumar: Real devices are more complex, it won't work.
- Walter: I can disprove this.
- The EDA tool must know the tap indexes.
- Kumar: The TX can send back coefficients at the end of training.
- TX buffers can have many architectures.
- Walter: We have to solve the system integrators' problem.
- RX Init can do everything.
- Kumar: An RX can't do that, not in the real world.
- Walter: The TX can optimize its taps and can communicate to the RX.
- The TX starts with no EQ.
- You give it a unit pulse response.
- Convolve with the channel and send to RX Init.
- Tell the RX what coefficients were used.
- The RX can run a simulation inside of itself, applying the TX coefficients.
- Init can call its own GetWave to do this, although this may take some time.
- Kumar: That's not what real devices do.
- The RX decides how to divide up the EQ between itself and the TX.
- Todd: Cadence is looking for literal emulation of the hardware process.
- That is OK, but there are other, quicker ways.
- Walter: With GetWave the adjustments are not made when the RX would actually
make them.
- Kumar: We need to model the real hardware process and also allow statistical
flow.
- The BIRD provides that.
- Silicon is in the GetWave model, Init is behavioral.
- Ambrish: The BIRD has a statistical flow.
- It is the most general approach.
- Todd: Users need to receive the required settings at the end of the process.
- Walter: In some cases the BIOS sets the CTLE.
- Some RX buffers auto-adapt and there is no need to report.
- The standard requires presets.
- Kumar: 802.3 says there must be an initial value.
- PCI says presets, IEEE only suggests that.
Walter: At DesignCON Huawei showed that training when cold doesn't work when
hot, and vice-versa.
- One can not rely on training.
- Kumar: We have provided the TX coefficients that were requested.
- That is a separate BIRD.
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Next meeting: 15 April 2014 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
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