Why does Quartus take 4 hours for a pin I/O change?

Sometimes the smart compile feature is great, but other times...  I
have a Stratix chip in Quartus II v4sp1.  All I did was go into
Assignment Editor and change a couple of pins from one I/O standard to
another. There were no changes to my RTL code.  As expected, it umped
through synthesis in a minute.  However, I expected the fitter to just
take a few minutes since there was no placement or routing changes.
Instead, it's taken 2 hours, and it's only at 51%.  This is about as
long as a full place and route.  Why is it doing this!?!?!?

 David

I believe you can prevent the re-route and place by changing the io
standards directly in the chipeditor. But that's only for a quick test of
course.

"David Rogoff" <david@therogoffs.com> wrote in message
news:zn6sn1mi.fsf@therogoffs.com...
>
> Sometimes the smart compile feature is great, but other times...  I
> have a Stratix chip in Quartus II v4sp1.  All I did was go into
> Assignment Editor and change a couple of pins from one I/O standard to
> another. There were no changes to my RTL code.  As expected, it umped
> through synthesis in a minute.  However, I expected the fitter to just
> take a few minutes since there was no placement or routing changes.
> Instead, it's taken 2 hours, and it's only at 51%.  This is about as
> long as a full place and route.  Why is it doing this!?!?!?
>
>  David

David Rogoff <david@therogoffs.com> wrote in message news:<zn6sn1mi.fsf@therogoffs.com>...
> Sometimes the smart compile feature is great, but other times...  I
> have a Stratix chip in Quartus II v4sp1.  All I did was go into
> Assignment Editor and change a couple of pins from one I/O standard to
> another. There were no changes to my RTL code.  As expected, it umped
> through synthesis in a minute.  However, I expected the fitter to just
> take a few minutes since there was no placement or routing changes.
> Instead, it's taken 2 hours, and it's only at 51%.  This is about as
> long as a full place and route.  Why is it doing this!?!?!?
> 
>  David

Hi David,

  You have several options available to speed up your compile time. 

1. The first one is using the Chip Editor along with the Resource
Property Editor. The Resource Property Editor is used for small ECO
type changes of the type that you have described. Details of how to
use these tools can be found in the Quartus Handbook.
http://www.altera.com/literature/hb/qts/qts_qii53010.pdf

2. The second solution is available from the command line/DOS prompt.
You will need to change directory to your project directory. Check
that quartus_fit is on your path. Then type in:
quartus_fit design_name --io_smart_recompile

3. Incremental fitting might work -- again it depends on if the change
in IO standard will force a pin-out change due to the IOs being
incompatible with their current bank.  Incremental fitting only saves
about 25% of the fit time on average though. This command is available
from the Processing->Start->Start Incremental Fitting menu in the UI.

Hope this helps.

Subroto Datta
Altera Corp.