Sergey Lapin wrote:
On Mon, Jun 20, 2011 at 4:44 PM, Laurent Gauch
<[email protected]> wrote:
only one transport option; autoselect 'jtag'
> interface_signal list
interface_signal list
Interface Signal Name | Mask | Value
----------------------------------------------------------
> interface_signal add led 8000
interface_signal add led 8000
There are no signals defined yet.
> interface_signal list
interface_signal list
Interface Signal Name | Mask | Value
----------------------------------------------------------
led | 0x00008000 | 0x00008000
> bitbang led=lo
bitbang led=lo
ftdi_write_data: USB device unavailable
Unable to write signal: led
in procedure 'bitbang'
> bitbang led
bitbang led
ftdi_write_data: USB device unavailable
Unable to read signal: led
in procedure 'bitbang'
Does OpenOCD need to handle this kind of bitbang fonction from TCL ?
For me, it does not, because it is too DANGEROUS for both the dongle and
target ...
PLEASE COMMENT
The problem is that the result of a bit-bang procedures will be dongle and
layout specific. There are too many chances for the end-user to create
short-circuit in the dongle or on the dongle port to the target board.
Also, we should not use and/or provide the possibility to the end-user to
manage himself the bitbang of the dongle port, from TCL or from any other
access.
This is JUST not the JOB of openocd but the job of other pieces of software
(as manufacturer post-production test program ...).
ALL dongle port access should be controlled and checked in the FT2232.c. The
FT2232 should not give to higher layer the possibility to have an direct
access to the dongle port.
Regards,
Laurent
http://www.amontec.com/jtagkey.shtml
Amontec JTAGkey-2 : HIGH SPEED USB JTAG CABLE ADAPTER DONGLE DRIVER
I don't think this is heavily an issue here.
As you say, this feature is not a issue. But I send a BIG WARNING HERE !
This functionality might
be disabled by default
and not recommended for inclusion in distributions.
WE HAVE TO MAKE SURE TO DO NOT *release* ANY OPENOCD WITH THIS FEATURE
ENABLED !!!
CEDEROM, do you have add an explicit define to enable this feature at
compilation. If not please send a patch.
But easy way to
write drivers for custom
dongles in config files heavily reduces costs of development and production.
True, for development & prototyping. False, for production.
I am certain this kind of bitbang TCL features, as it is now, will make
the OpenOCD unstable at long term, since it bypass layout specification
at higher software level.
There are big differences between the "How to bitbang the FT2232" and
"How to bitbang a specific dongle layout-port".
Yes, it is easy but NOT SAFE for the end-user.
S.
Regards,
Laurent
http://www.amontec.com/jtagkey.shtml
Amontec JTAGkey-2 : HIGH SPEED USB JTAG CABLE ADAPTER DONGLE DRIVER
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