drm/amd/display: Check null pointers before multiple uses

[WHAT & HOW]
Poniters, such as stream_enc and dc->bw_vbios, are null checked previously
in the same function, so Coverity warns "implies that stream_enc and
dc->bw_vbios might be null". They are used multiple times in the
subsequent code and need to be checked.

This fixes 10 FORWARD_NULL issues reported by Coverity.
Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -636,7 +636,8 @@ void hwss_build_fast_sequence(struct dc *dc,
 	while (current_pipe) {
 		current_mpc_pipe = current_pipe;
 		while (current_mpc_pipe) {
-			if (dc->hwss.set_flip_control_gsl && current_mpc_pipe->plane_state && current_mpc_pipe->plane_state->update_flags.raw) {
+			if (current_mpc_pipe->plane_state) {
+				if (dc->hwss.set_flip_control_gsl && current_mpc_pipe->plane_state->update_flags.raw) {
 					block_sequence[*num_steps].params.set_flip_control_gsl_params.pipe_ctx = current_mpc_pipe;
 					block_sequence[*num_steps].params.set_flip_control_gsl_params.flip_immediate = current_mpc_pipe->plane_state->flip_immediate;
 					block_sequence[*num_steps].func = HUBP_SET_FLIP_CONTROL_GSL;
@@ -688,6 +689,7 @@ void hwss_build_fast_sequence(struct dc *dc,
 					block_sequence[*num_steps].func = DPP_PROGRAM_BIAS_AND_SCALE;
 					(*num_steps)++;
 				}
+			}
 			if (hws->funcs.set_output_transfer_func && current_mpc_pipe->stream->update_flags.bits.out_tf) {
 				block_sequence[*num_steps].params.set_output_transfer_func_params.dc = dc;
 				block_sequence[*num_steps].params.set_output_transfer_func_params.pipe_ctx = current_mpc_pipe;

drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c

@@ -2284,6 +2284,9 @@ void dcn20_post_unlock_program_front_end(
 		}
 	}
 
+	if (!hwseq)
+		return;
+
 	/* P-State support transitions:
 	 * Natural -> FPO: 		P-State disabled in prepare, force disallow anytime is safe
 	 * FPO -> Natural: 		Unforce anytime after FW disable is safe (P-State will assert naturally)
@@ -2291,7 +2294,7 @@ void dcn20_post_unlock_program_front_end(
 	 * FPO -> Unsupported:	P-State disabled in prepare, unforce disallow anytime is safe
 	 * FPO <-> SubVP:		Force disallow is maintained on the FPO / SubVP pipes
 	 */
-	if (hwseq && hwseq->funcs.update_force_pstate)
+	if (hwseq->funcs.update_force_pstate)
 		dc->hwseq->funcs.update_force_pstate(dc, context);
 
 	/* Only program the MALL registers after all the main and phantom pipes
@@ -2531,6 +2534,9 @@ bool dcn20_wait_for_blank_complete(
 {
 	int counter;
 
+	if (!opp)
+		return false;
+
 	for (counter = 0; counter < 1000; counter++) {
 		if (!opp->funcs->dpg_is_pending(opp))
 			break;

drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c

@@ -804,8 +804,11 @@ bool dp_set_test_pattern(
 			break;
 		}
 
+		if (!pipe_ctx->stream)
+			return false;
+
 		if (pipe_ctx->stream_res.tg->funcs->lock_doublebuffer_enable) {
-			if (pipe_ctx->stream && should_use_dmub_lock(pipe_ctx->stream->link)) {
+			if (should_use_dmub_lock(pipe_ctx->stream->link)) {
 				union dmub_hw_lock_flags hw_locks = { 0 };
 				struct dmub_hw_lock_inst_flags inst_flags = { 0 };
 

drivers/gpu/drm/amd/display/dc/link/hwss/link_hwss_dio.c

@@ -74,7 +74,10 @@ void reset_dio_stream_encoder(struct pipe_ctx *pipe_ctx)
 	struct link_encoder *link_enc = link_enc_cfg_get_link_enc(pipe_ctx->stream->link);
 	struct stream_encoder *stream_enc = pipe_ctx->stream_res.stream_enc;
 
-	if (stream_enc && stream_enc->funcs->disable_fifo)
+	if (!stream_enc)
+		return;
+
+	if (stream_enc->funcs->disable_fifo)
 		stream_enc->funcs->disable_fifo(stream_enc);
 	if (stream_enc->funcs->set_input_mode)
 		stream_enc->funcs->set_input_mode(stream_enc, 0);

drivers/gpu/drm/amd/display/dc/resource/dce112/dce112_resource.c

@@ -1067,7 +1067,10 @@ static void bw_calcs_data_update_from_pplib(struct dc *dc)
 	struct dm_pp_clock_levels clks = {0};
 	int memory_type_multiplier = MEMORY_TYPE_MULTIPLIER_CZ;
 
-	if (dc->bw_vbios && dc->bw_vbios->memory_type == bw_def_hbm)
+	if (!dc->bw_vbios)
+		return;
+
+	if (dc->bw_vbios->memory_type == bw_def_hbm)
 		memory_type_multiplier = MEMORY_TYPE_HBM;
 
 	/*do system clock  TODO PPLIB: after PPLIB implement,

drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c

@@ -1651,6 +1651,9 @@ static void dcn32_enable_phantom_plane(struct dc *dc,
 		else
 			phantom_plane = dc_state_create_phantom_plane(dc, context, curr_pipe->plane_state);
 
+		if (!phantom_plane)
+			continue;
+
 		memcpy(&phantom_plane->address, &curr_pipe->plane_state->address, sizeof(phantom_plane->address));
 		memcpy(&phantom_plane->scaling_quality, &curr_pipe->plane_state->scaling_quality,
 				sizeof(phantom_plane->scaling_quality));

drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource_helpers.c

@@ -218,7 +218,6 @@ bool dcn32_is_center_timing(struct pipe_ctx *pipe)
 				pipe->stream->timing.v_addressable != pipe->stream->src.height) {
 			is_center_timing = true;
 		}
-	}
 
 		if (pipe->plane_state) {
 			if (pipe->stream->timing.v_addressable != pipe->plane_state->dst_rect.height &&
@@ -226,6 +225,7 @@ bool dcn32_is_center_timing(struct pipe_ctx *pipe)
 				is_center_timing = true;
 			}
 		}
+	}
 
 	return is_center_timing;
 }