commit f70eddafbc2c6045a14e2f8bbb3273ee738fbaf7
author Arthur Heymans <arthur@aheymans.xyz> Tue Aug 21 18:37:00 2018 +0200
committer Nico Huber <nico.h@gmx.de> Wed Aug 22 10:30:08 2018 +0000
tree 9f110da02c1a579f3d853b84dfdbd21a3468eb81
parent d58de7d2126316fc1afbb84e4d6a26046d2cf1b7

gma pipe_setup: Work around a PFIT_CONTROL quirk on G45

In legacy VGA mode the pillarbox scaling mode fails to display anything, so just
always force 'auto' mode, which will have the output stretched to fullscreen.

Change-Id: Ie7b7be06b5c5bd5569e8a6645dd9359660f7a51a
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/28255
Reviewed-by: Nico Huber <nico.h@gmx.de>

common/hw-gfx-gma-pipe_setup.adb

diff --git a/common/hw-gfx-gma-pipe_setup.adb b/common/hw-gfx-gma-pipe_setup.adb
index 50b63e5..a237de7 100644
--- a/common/hw-gfx-gma-pipe_setup.adb
+++ b/common/hw-gfx-gma-pipe_setup.adb
@@ -552,8 +552,15 @@
                when Secondary => GMCH_PFIT_CONTROL_SELECT_PIPE_B,
                when others    => 0);
 
+      -- Work around a quirk:
+      -- In legacy VGA mode Pillarbox fails to display anything so just force
+      -- 'auto' mode on all displays, which will the output stretched to
+      -- fullscreen .
       PF_Ctrl_Scaling : constant Word32 :=
-         GMCH_PFIT_CONTROL_SCALING (Scaling_Type (Framebuffer, Mode));
+        (if Framebuffer.Offset = VGA_PLANE_FRAMEBUFFER_OFFSET then
+           GMCH_PFIT_CONTROL_SCALING (Uniform)
+         else
+           GMCH_PFIT_CONTROL_SCALING (Scaling_Type (Framebuffer, Mode)));
 
       In_Use : Boolean;
    begin