David Brownell wrote:
On Thursday 15 April 2010, Laurent Gauch wrote:
relation ship with a dedicated interface.cfg ;-(
THE solution is to add new argument on the j
tag newtap.
Disagree .... it's simpler all around just to bugfix the
broken config files (In this case there sem to be driver
bugs too, which is why the failure mode is dongle-specific.
I can understand you are disagreeing with my comments.
I do not want to noise the mailing list at all. For sure.
What is the solution when a dongle is capable to up to 30Mhz or more,
but the target do not support so much JTAG TCK frequency.
(I am talking after initialization of the chip, the PLL ...)
(In the particular case, PXA2xx are just not able to run at 30MHz)
Note : we have checked Amontec JTAGkey-2 and Amontec JTAGkey-2P at 30Mhz
to program a Xilinx Spartan-6, so the JTAG frequency is depending first
on the target TAP, then on the chain itslef, then on the capability of
the dongle.
Also, please let me know why in a BSDL file ( Boundary Scan Description
File ) the first attribute coming is the max frequency of the TARGET TAP?
That's exactly what is missing in the jtag newtap of openocd ! The jtag
newtap is really close to the definition of the BSDL files itself (I
mean max frequency , ir length, idcode ...).
When creating a new jtag tap we should give the max frequency of the TAP
(target specific). At the end of the jtag chain construction (or after
each jtag newtap) we could check and found the smaller freq max of all
tap. This will give us the theoretical max freq of the chain itself
(JTAG daisy chain). Then if the dongle (ex. the Amontec JTAGkey-2) is
able to run over the max freq of the chain itslef we will limit the
frequency automatically regarding the result of the freq max of the
chain itself.
Without this mecanism, we will return to many custom .cfg -> as at the
begin of OpenOCD 2004 when we were running with only ONE .cfg !
One other solution could be to auto-detect the max frequency after
adding a new tap, by checking the IDCode of the TAP varying the
frequency ! This could be a very nice solution (certainly the best
solution), but not really easy to implement !
Laurent
http://www.amontec.com
http://www.amontec.com/jtagkey.shtml
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