[S] Change in libgfxinit[master]: common: Turn off VGA when not in use anymore

[Stefan Reinauer (Code Review)]

Stefan Reinauer has submitted this change. ( https://review.coreboot.org/c/libgfxinit/+/72123 )

(

3 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
 )Change subject: common: Turn off VGA when not in use anymore
......................................................................

common: Turn off VGA when not in use anymore

When VGA mode is up on Alder Lake or Raptor Lake devices,
`Update_Outputs' does successfully turn off graphics but it also
leaves some undesirable configuration which can confuse following
graphics drivers such as the PEIM graphics driver.

Experimentally, we have identified that `libgfxinit' should turn off
VGA when it disables the ouput which was using this mode.

BUG=b:264526798
BRANCH=firmware-brya-14505.B
TEST=Developer screen shows up on the recovery flow on skolas

Change-Id: Id39c308a4d0408b996834439186645b33e692d02
Signed-off-by: Jeremy Compostella 
Reviewed-on: https://review.coreboot.org/c/libgfxinit/+/72123
Reviewed-by: Tarun Tuli 
Reviewed-by: Nick Vaccaro 
Tested-by: Stefan Reinauer 
---
M common/hw-gfx-gma.adb
1 file changed, 30 insertions(+), 0 deletions(-)

Approvals:
  Stefan Reinauer: Verified
  Nick Vaccaro: Looks good to me, approved
  Jérémy Compostella: Looks good to me, but someone else must approve
  Tarun Tuli: Looks good to me, approved

diff --git a/common/hw-gfx-gma.adb b/common/hw-gfx-gma.adb
index 1db493f..4a1050e 100644
--- a/common/hw-gfx-gma.adb
+++ b/common/hw-gfx-gma.adb
@@ -210,6 +210,10 @@
            ("Disabling port " & Port_Names (Pipe_Cfg.Port)));
          pragma Debug (Debug.New_Line);

+         if Pipe_Cfg.Framebuffer.Offset = VGA_PLANE_FRAMEBUFFER_OFFSET then
+            Display_Controller.Legacy_VGA_Off;
+         end if;
+
          Connectors.Pre_Off (Port_Cfg);
          Display_Controller.Off (Pipe);
          Connectors.Post_Off (Port_Cfg);