drm/amd/display: stop doing unnecessary detection when going to D3

[Why]
Don't want to start HW discovery unless we have lost power,
as doing rediscovery otherwise is both unnecessary and time consuming.
Before this change it takes 40 seconds to go in to suspend, after it
takes 27 seconds

[How]
Accelerated mode gets cleared if we lose power. Only do detection if
this register is cleared
Signed-off-by: Joseph Gravenor <joseph.gravenor@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -1318,6 +1318,12 @@ bool dc_commit_state(struct dc *dc, struct dc_state *context)
 	return (result == DC_OK);
 }
 
+bool dc_is_hw_initialized(struct dc *dc)
+{
+	struct dc_bios *dcb = dc->ctx->dc_bios;
+	return dcb->funcs->is_accelerated_mode(dcb);
+}
+
 bool dc_post_update_surfaces_to_stream(struct dc *dc)
 {
 	int i;

drivers/gpu/drm/amd/display/dc/dc.h

@@ -1069,6 +1069,7 @@ unsigned int dc_get_current_backlight_pwm(struct dc *dc);
 unsigned int dc_get_target_backlight_pwm(struct dc *dc);
 
 bool dc_is_dmcu_initialized(struct dc *dc);
+bool dc_is_hw_initialized(struct dc *dc);
 
 enum dc_status dc_set_clock(struct dc *dc, enum dc_clock_type clock_type, uint32_t clk_khz, uint32_t stepping);
 void dc_get_clock(struct dc *dc, enum dc_clock_type clock_type, struct dc_clock_config *clock_cfg);