drm/amd/display: fix eDP fast bootup for pre-raven asic

[Why]
For fastboot, Bios will light up eDP before SW driver is loaded. SW
driver will check if eDP is lit by bios through reading the
BIOS_SCRATCH_3 register. If lit, SW driver will not power down eDP
power and phy to save time.

Definition of BIOS_SCRATCH_3 are missing for pre-raven asic. This
causes eDP fast boot to not work property. For some eDP panels, even
if dp tx sends NoVideoStream_flag =1 and dpcd 0x600=2, eDP rx may not
handle properly. This may cause a short flash on screen.

[How] Add definition of BIOS_SCRATCH_3 for all asic

Signed-off-by: hersen wu <hersenxs.wu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Acked-by: Yongqiang Sun <yongqiang.sun@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser_helper.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser_helper.c
index fdda8aa8e303..d8275ceb20c1 100644
--- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser_helper.c
+++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser_helper.c
@@ -83,8 +83,7 @@ uint32_t bios_get_vga_enabled_displays(
 {
 	uint32_t active_disp = 1;
 
-	if (bios->regs->BIOS_SCRATCH_3) /*follow up with other asic, todo*/
-		active_disp = REG_READ(BIOS_SCRATCH_3) & 0XFFFF;
+	active_disp = REG_READ(BIOS_SCRATCH_3) & 0XFFFF;
 	return active_disp;
 }