Fix Luminary FT2232 layout docs/configs

Most of this patch updates documentation and comments for various
Luminary boards, supporting two bug fixes by helping to make sense
of the current mess:

 - Recent rev C lm3s811 eval boards didn't work.  They must use
   the ICDI layout, which sets up some signals that the older
   boards didn't need.  This is actually safe and appropriate
   for *all* recent boards ... so just make "luminary.cfg" use
   the ICDI layout.

 - "luminary-lm3s811.cfg", was previously unusable!  No VID/PID;
   and the wrong vendor string.  Make it work, but reserve it
   for older boards where the ICDI layout is wrong.

 - Default the LM3748 eval board to "luminary.cfg", like the
   other boards.  If someone uses an external JTAG adapter, all
   boards will use the same workaround (override that default).

The difference between the two FT2232 layouts is that eventually
the EVB layout will fail cleanly when asked to enable SWO trace,
but the ICDI layout will as cleanly be able to enable it.  Folk
using "luminary.cfg" with Rev B boards won't see anything going
wrong until SWO support is (someday) added.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/jtag/drivers/ft2232.c b/src/jtag/drivers/ft2232.c
index 831a5dca..06fc2523 100644
--- a/src/jtag/drivers/ft2232.c
+++ b/src/jtag/drivers/ft2232.c
@@ -2182,6 +2182,11 @@ static int usbjtag_init(void)
 	}
 	else if (strcmp(ft2232_layout, "evb_lm3s811") == 0)
 	{
+		/* There are multiple revisions of LM3S811 eval boards:
+		 * - Rev B (and older?) boards have no SWO trace support.
+		 * - Rev C boards add ADBUS_6 DBG_ENn and BDBUS_4 SWO_EN;
+		 *   they should use the "luminary_icdi" layout instead.
+		 */
 		nTRST = 0x0;
 		nTRSTnOE = 0x00;
 		nSRST = 0x20;
@@ -2191,6 +2196,9 @@ static int usbjtag_init(void)
 	}
 	else if (strcmp(ft2232_layout, "luminary_icdi") == 0)
 	{
+		/* Most Luminary eval boards support SWO trace output,
+		 * and should use this "luminary_icdi" layout.
+		 */
 		nTRST = 0x0;
 		nTRSTnOE = 0x00;
 		nSRST = 0x20;