drm/amd/display: Exit from idle state before accessing HW data

[why & how]
User interface cannot guarantee system is in
idle state, so need to ensure we exit idle state
before accessing any HW data.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c

@@ -64,11 +64,15 @@ static void dmub_abm_init_ex(struct abm *abm, uint32_t backlight)
 
 static unsigned int dmub_abm_get_current_backlight_ex(struct abm *abm)
 {
+	dc_allow_idle_optimizations(abm->ctx->dc, false);
+
 	return dmub_abm_get_current_backlight(abm);
 }
 
 static unsigned int dmub_abm_get_target_backlight_ex(struct abm *abm)
 {
+	dc_allow_idle_optimizations(abm->ctx->dc, false);
+
 	return dmub_abm_get_target_backlight(abm);
 }