Re: [Openocd-development] OMAP3 JTAG, was: JTAG

[Rick Altherr]

On Feb 24, 2009, at 9:37 AM, Dirk Behme wrote:

Rick Altherr wrote:

On Feb 19, 2009, at 10:01 PM, Kees Jongenburger wrote:

Hello Rick,

On Fri, Feb 20, 2009 at 12:47 AM, Rick Altherr <kc8...@kc8apf.net> wrote:

On Feb 19, 2009, at 3:38 PM, Kees Jongenburger wrote:

Can you write up the problems you encountered with OpenOCD?  There
are a few
people on the OpenOCD development list who are actively working on
fixing up
the JTAG layer.  If we could get some data as to what isn't working
and what
is needed, we can start working on the necessary improvements.

Let us start with these improvements now!

Just need someone with time and knowledge. I have the latter and not the former.

There are currently problems that possibly prevent the OpenOCD from
adding
the DAP.


This does not match
what the ICEPICK wants. I don't know it this is a problem or not

1) When performing ir/dr scans the default end state is Run Test Idle.

as simple as allowing an extra argument to the irscan and drscan
commands in the TCL layer.

I know that the JTAG internals in OpenOCD can support this. It may be

2) The tap_move that allows moving between "stable" tap states does
not follow "shortest pad"
but always takes 7 steps, possibly passing via test logic reset. I
mailed about it
https://lists.berlios.de/pipermail/openocd-development/2009-February/004625.html

Yes.  I remember seeing the query about this, but I didn't realize it
was a limiting issue for ICEPICK.

3) There is no support for generating clock pulses in the IDLE state.

but this is required

The internals have support for this as it was needed for SVF support.
Again, it may just need to be exposed at the TCL layer.

It is my understanding that we need 1, 2 and 3 fixed/improved to get
OMAP3 (ARM) access with OpenOCD. Correct?

Are there already any patches, proposals or e.g. pseudo code available
for these three topics?

Not currently.

Being not so familiar with OpenOCD code,
something like this would help as a starting point. Strings like "need
to be exposed at the TCL layer"

That means that a call to register_command needs to be made so that the TCL interpreter knows that the new command exists and what C function to call when it is executed. For #3, a new C function needs to be added that parses the arguments and calls the JTAG method for clocking in idle. I think run_test may already do that.

or "extra argument to the irscan and
drscan commands in the TCL layer"

This just means that the C function for the irscan and drscan commands needs to look for another argument (namely the end state) and add a call to jtag_set_end_state. This might also be handled already with a 'end_state' command.

sound a little too abstract for me.
Sorry ;)

I will look into OpenOCD code, now.

Best regards

Dirk


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--
Rick Altherr
kc8...@kc8apf.net


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