drm/amd/display: Fix S4 hang polling on HW power up done for VBIOS DMCUB

[Why]
VBIOS DMCUB firmware doesn't set the dal_fw bit and we end up hanging
waiting for HW power up done because of it.

[How]
Simplify the path and allow mailbox_rdy to be a functional check when
we detect VBIOS firmware.
Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dmub/src/dmub_dcn35.c

@@ -555,8 +555,14 @@ uint32_t dmub_dcn35_read_inbox0_ack_register(struct dmub_srv *dmub)
 bool dmub_dcn35_is_hw_powered_up(struct dmub_srv *dmub)
 {
 	union dmub_fw_boot_status status;
+	uint32_t is_enable;
+
+	REG_GET(DMCUB_CNTL, DMCUB_ENABLE, &is_enable);
+	if (is_enable == 0)
+		return false;
 
 	status.all = REG_READ(DMCUB_SCRATCH0);
 
-	return status.bits.hw_power_init_done;
+	return (status.bits.dal_fw && status.bits.hw_power_init_done && status.bits.mailbox_rdy) ||
+	       (!status.bits.dal_fw && status.bits.mailbox_rdy);
 }

drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c

@@ -800,20 +800,13 @@ enum dmub_status dmub_srv_cmd_execute(struct dmub_srv *dmub)
 
 bool dmub_srv_is_hw_pwr_up(struct dmub_srv *dmub)
 {
-	union dmub_fw_boot_status status;
-
 	if (!dmub->hw_funcs.is_hw_powered_up)
 		return true;
 
 	if (!dmub->hw_funcs.is_hw_powered_up(dmub))
 		return false;
 
-	if (!dmub->hw_funcs.is_hw_init(dmub))
-		return false;
-
-	status = dmub->hw_funcs.get_fw_status(dmub);
-
-	return status.bits.dal_fw && status.bits.mailbox_rdy;
+	return true;
 }
 
 enum dmub_status dmub_srv_wait_for_hw_pwr_up(struct dmub_srv *dmub,