gma i2c: Make I2C port for VGA displays a config option

Boards with a DVI-I connector share the I2C pins for both analog and
digital displays. In that case, the EDID for a VGA display has to be
read over the I2C interface of the coupled digital port.

TEST=Booted kontron/ktqm77 with DVI-I to VGA cable. Display is detected
     and enabled (but doesn't show anything, yet?).

Change-Id: I5c4f77d5ad1927f075877a3719361ed2193f4c39
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/17086
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
13 files changed
tree: 7703f06d76adeaf58b1fd9c8980716410c92909d
  1. common/
  2. configs/
  3. .gitignore
  4. COPYING
  5. Makefile
  6. Makefile.inc
  7. TODO