drm/amd/display: Fix takover from VGA mode

HW Engineer's Notes:
 During switch from vga->extended, if we set the VGA_TEST_ENABLE and then
 hit the VGA_TEST_RENDER_START, then the DCHUBP timing gets updated correctly.
 Then vBIOS will have it poll for the VGA_TEST_RENDER_DONE and unset
 VGA_TEST_ENABLE, to leave it in the same state as before.

Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Bhawanpreet Lakha
2018-02-27 12:12:46 -05:00
committed by Alex Deucher
parent 316178f072
commit 90e3103e19
2 changed files with 18 additions and 2 deletions

View File

@@ -224,6 +224,16 @@ static void disable_vga(
REG_WRITE(D2VGA_CONTROL, 0);
REG_WRITE(D3VGA_CONTROL, 0);
REG_WRITE(D4VGA_CONTROL, 0);
/* HW Engineer's Notes:
* During switch from vga->extended, if we set the VGA_TEST_ENABLE and
* then hit the VGA_TEST_RENDER_START, then the DCHUBP timing gets updated correctly.
*
* Then vBIOS will have it poll for the VGA_TEST_RENDER_DONE and unset
* VGA_TEST_ENABLE, to leave it in the same state as before.
*/
REG_UPDATE(VGA_TEST_CONTROL, VGA_TEST_ENABLE, 1);
REG_UPDATE(VGA_TEST_CONTROL, VGA_TEST_RENDER_START, 1);
}
static void dpp_pg_control(