David Brownell <david-b@pacbell.net>:

Minor updates to the text about reset configuration:

 - Mention a new point that it interacts with JTAG routers;

 - Talk about a "user" config file not a "system" one;

 - Remove text from the "reset_config" description; instead,
   cross-reference the more extensive text earlier.
   


git-svn-id: svn://svn.berlios.de/openocd/trunk@2243 b42882b7-edfa-0310-969c-e2dbd0fdcd60
This commit is contained in:
zwelch 2009-06-16 00:22:12 +00:00
parent 1ac220df71
commit cc9488008a
1 changed files with 15 additions and 13 deletions

View File

@ -1911,6 +1911,7 @@ configuration. This can also be quite confusing.
Resets also interact with @var{reset-init} event handlers,
which do things like setting up clocks and DRAM, and
JTAG clock rates. (@xref{JTAG Speed}.)
They can also interact with JTAG routers.
Please see the various board files for examples.
@quotation Note
@ -1919,11 +1920,12 @@ Reset configuration touches several things at once.
Normally the board configuration file
should define it and assume that the JTAG adapter supports
everything that's wired up to the board's JTAG connector.
However, the target configuration file could also make note
of something the silicon vendor has done inside the chip,
which will be true for most (or all) boards using that chip.
And when the JTAG adapter doesn't support everything, the
system configuration file will need to override parts of
user configuration file will need to override parts of
the reset configuration provided by other files.
@end quotation
@ -1967,6 +1969,7 @@ and @command{reset init} commands; after @command{reset init} a
board-specific script might do things like setting up DRAM.
(@xref{Reset Command}.)
@anchor{SRST and TRST Issues}
@section SRST and TRST Issues
Because SRST and TRST are hardware signals, they can have a
@ -1979,9 +1982,11 @@ common issues are:
SRST or TRST to the JTAG connector. Some JTAG adapters don't
support such signals even if they are wired up.
Use the @command{reset_config} @var{signals} options to say
when one of those signals is not connected.
when either of those signals is not connected.
When SRST is not available, your code might not be able to rely
on controllers having been fully reset during code startup.
Missing TRST is not a problem, since JTAG level resets can
be triggered using with TMS signaling.
@item @emph{Signals shorted} ... Sometimes a chip, board, or
adapter will connect SRST to TRST, instead of keeping them separate.
@ -2051,17 +2056,14 @@ This command tells OpenOCD the reset configuration
of your combination of JTAG board and target in target
configuration scripts.
If you have an interface that does not support SRST and
TRST(unlikely), then you may be able to work around that
problem by using a reset_config command to override any
settings in the target configuration script.
SRST and TRST has a fairly well understood definition and
behaviour in the JTAG specification, but vendors take
liberties to achieve various more or less clearly understood
goals. Sometimes documentation is available, other times it
is not. OpenOCD has the reset_config command to allow OpenOCD
to deal with the various common cases.
Information earlier in this section describes the kind of problems
the command is intended to address (@pxref{SRST and TRST Issues}).
As a rule this command belongs only in board config files,
describing issues like @emph{board doesn't connect TRST};
or in user config files, addressing limitations derived
from a particular combination of interface and board.
(An unlikely example would be using a TRST-only adapter
with a board that only wires up SRST.)
The @var{mode_flag} options can be specified in any order, but only one
of each type -- @var{signals}, @var{combination}, @var{trst_type},