drm/amd/display: Destroy DC context while keeping DML and DML2

If there is memory pressure at suspend time then dynamically
allocating a large structure as part of DC suspend code will
fail.

Instead re-use the same structures and clear all members except
those that should be maintained.

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2362Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -4781,12 +4781,6 @@ bool dc_set_power_state(
 	struct dc *dc,
 	enum dc_acpi_cm_power_state power_state)
 {
-	struct kref refcount;
-	struct display_mode_lib *dml;
-#ifdef CONFIG_DRM_AMD_DC_FP
-	struct dml2_context *dml2 = NULL;
-#endif
-
 	if (!dc->current_state)
 		return true;
 
@@ -4805,40 +4799,9 @@ bool dc_set_power_state(
 
 		break;
 	default:
-#ifdef CONFIG_DRM_AMD_DC_FP
-		if (dc->debug.using_dml2)
-			dml2 = dc->current_state->bw_ctx.dml2;
-#endif
 		ASSERT(dc->current_state->stream_count == 0);
-		/* Zero out the current context so that on resume we start with
-		 * clean state, and dc hw programming optimizations will not
-		 * cause any trouble.
-		 */
-		dml = kzalloc(sizeof(struct display_mode_lib),
-				GFP_KERNEL);
-
-		ASSERT(dml);
-		if (!dml)
-			return false;
-
-		/* Preserve refcount */
-		refcount = dc->current_state->refcount;
-		/* Preserve display mode lib */
-		memcpy(dml, &dc->current_state->bw_ctx.dml, sizeof(struct display_mode_lib));
 
 		dc_resource_state_destruct(dc->current_state);
-		memset(dc->current_state, 0,
-				sizeof(*dc->current_state));
-
-		dc->current_state->refcount = refcount;
-		dc->current_state->bw_ctx.dml = *dml;
-
-		kfree(dml);
-
-#ifdef CONFIG_DRM_AMD_DC_FP
-		if (dc->debug.using_dml2)
-			dc->current_state->bw_ctx.dml2 = dml2;
-#endif
 
 		break;
 	}

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

@@ -4487,6 +4487,18 @@ void dc_resource_state_destruct(struct dc_state *context)
 		context->streams[i] = NULL;
 	}
 	context->stream_count = 0;
+	context->stream_mask = 0;
+	memset(&context->res_ctx, 0, sizeof(context->res_ctx));
+	memset(&context->pp_display_cfg, 0, sizeof(context->pp_display_cfg));
+	memset(&context->dcn_bw_vars, 0, sizeof(context->dcn_bw_vars));
+	context->clk_mgr = NULL;
+	memset(&context->bw_ctx.bw, 0, sizeof(context->bw_ctx.bw));
+	memset(context->block_sequence, 0, sizeof(context->block_sequence));
+	context->block_sequence_steps = 0;
+	memset(context->dc_dmub_cmd, 0, sizeof(context->dc_dmub_cmd));
+	context->dmub_cmd_count = 0;
+	memset(&context->perf_params, 0, sizeof(context->perf_params));
+	memset(&context->scratch, 0, sizeof(context->scratch));
 }
 
 void dc_resource_state_copy_construct(