drm/amd/display: Clean up NULL pointer warnings in dml2

This commit addresses multiple warnings by adding defensive
checks for NULL pointers before dereferencing them. The changes ensure
that pointers such as are validated, preventing potential undefined
behavior.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Gaghik Khachatrian <gaghik.khachatrian@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 38 insertions, 3 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_mall_phantom.c b/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_mall_phantom.c
index 66040c877d68..d56e58ce26c7 100644
--- a/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_mall_phantom.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2_0/dml2_mall_phantom.c
@@ -357,7 +357,7 @@ static bool enough_pipes_for_subvp(struct dml2_context *ctx, struct dc_state *st
  */
 static bool subvp_subvp_schedulable(struct dml2_context *ctx, struct dc_state *context)
 {
-	struct pipe_ctx *subvp_pipes[2];
+	struct pipe_ctx *subvp_pipes[2] = { NULL, NULL };
 	struct dc_stream_state *phantom = NULL;
 	uint32_t microschedule_lines = 0;
 	uint32_t index = 0;
@@ -369,6 +369,9 @@ static bool subvp_subvp_schedulable(struct dml2_context *ctx, struct dc_state *c
 		struct pipe_ctx *pipe = &context->res_ctx.pipe_ctx[i];
 		uint32_t time_us = 0;
 
+		if (pipe == NULL || pipe->stream == NULL)
+			continue;
+
 		/* Loop to calculate the maximum microschedule time between the two SubVP pipes,
 		 * and also to store the two main SubVP pipe pointers in subvp_pipes[2].
 		 */
@@ -386,14 +389,19 @@ static bool subvp_subvp_schedulable(struct dml2_context *ctx, struct dc_state *c
 			if (time_us > max_microschedule_us)
 				max_microschedule_us = time_us;
 
-			subvp_pipes[index] = pipe;
-			index++;
+			if (index < 2)
+				subvp_pipes[index++] = pipe;
 
 			// Maximum 2 SubVP pipes
 			if (index == 2)
 				break;
 		}
 	}
+
+	/* Minimal guard to avoid C6001 before subvp_pipes[0]/[1] dereference */
+	if (index < 2 || !subvp_pipes[0] || !subvp_pipes[1])
+		return false;
+
 	vactive1_us = ((subvp_pipes[0]->stream->timing.v_addressable * subvp_pipes[0]->stream->timing.h_total) /
 			(double)(subvp_pipes[0]->stream->timing.pix_clk_100hz * 100)) * 1000000;
 	vactive2_us = ((subvp_pipes[1]->stream->timing.v_addressable * subvp_pipes[1]->stream->timing.h_total) /
@@ -459,6 +467,11 @@ bool dml2_svp_drr_schedulable(struct dml2_context *ctx, struct dc_state *context
 			break;
 	}
 
+	if (pipe == NULL || pipe->stream == NULL) {
+		// Defensive: should never happen, try to catch in debug
+		ASSERT(0);
+		return false;
+	}
 	phantom_stream = ctx->config.svp_pstate.callbacks.get_paired_subvp_stream(context, pipe->stream);
 	main_timing = &pipe->stream->timing;
 	phantom_timing = &phantom_stream->timing;
@@ -549,6 +562,13 @@ static bool subvp_vblank_schedulable(struct dml2_context *ctx, struct dc_state *
 		if (!subvp_pipe && pipe_mall_type == SUBVP_MAIN)
 			subvp_pipe = pipe;
 	}
+
+	if (subvp_pipe == NULL) {
+		// Defensive: should never happen, catch in debug
+		ASSERT(0);
+		return false;
+	}
+
 	// Use ignore_msa_timing_param flag to identify as DRR
 	if (found && context->res_ctx.pipe_ctx[vblank_index].stream->ignore_msa_timing_param) {
 		// SUBVP + DRR case
@@ -753,6 +773,12 @@ static void enable_phantom_plane(struct dml2_context *ctx,
 				return;
 		}
 
+		/* Minimal NULL guard for C6011 */
+		if (!phantom_plane) {
+			ASSERT(0);
+			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));
@@ -880,6 +906,11 @@ bool dml2_svp_add_phantom_pipe_to_dc_state(struct dml2_context *ctx, struct dc_s
 	if (ctx->config.svp_pstate.force_disable_subvp)
 		return false;
 
+	if (!state) {
+		ASSERT(0);
+		return false;
+	}
+
 	if (!all_pipes_have_stream_and_plane(ctx, state))
 		return false;
 
@@ -898,6 +929,10 @@ bool dml2_svp_add_phantom_pipe_to_dc_state(struct dml2_context *ctx, struct dc_s
 	}
 
 	if (enough_pipes_for_subvp(ctx, state) && assign_subvp_pipe(ctx, state, &dc_pipe_idx)) {
+		if (state->res_ctx.pipe_ctx[dc_pipe_idx].stream == NULL) {
+			ASSERT(0);
+			return false;
+		}
 		dml_pipe_idx = dml2_helper_find_dml_pipe_idx_by_stream_id(ctx, state->res_ctx.pipe_ctx[dc_pipe_idx].stream->stream_id);
 		svp_height = mode_support_info->SubViewportLinesNeededInMALL[dml_pipe_idx];
 		vstartup = dml_get_vstartup_calculated(&ctx->v20.dml_core_ctx, dml_pipe_idx);