drm/amd/display: Recreate private_obj->state during S3 resume

[Why]

When entering S3, amdgpu first calls DRM to cache the current atomic
state, then commit the 'all-disabled' state. This sets dc->current_state
to point at the private atomic object's dm_atomic_state->context, as
any regular atomic commit would.

Afterwards, amdgpu_dm calls dc_set_power_state() with S3 power state.
This invalidates dc->current_state by wiping it to 0, consequently
wiping dm_atomic_state->context.

During resume, the cached atomic state is restored. When getting the
private object however, the dm_atomic_state - containing the wiped
context - is duplicated into the atomic state. This causes DC validation
to fail during atomic check, as necessary function pointers in dc_state
are now NULL.

[How]

Recreate the private object's dm_atomic_state->context during resume,
restoring any static values such as function pointers.

A TODO item is added to move static read-only values out of dc_state -
they shouldn't be there anyways.

Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -983,9 +983,16 @@ static int dm_resume(void *handle)
 	struct drm_plane *plane;
 	struct drm_plane_state *new_plane_state;
 	struct dm_plane_state *dm_new_plane_state;
+	struct dm_atomic_state *dm_state = to_dm_atomic_state(dm->atomic_obj.state);
 	enum dc_connection_type new_connection_type = dc_connection_none;
 	int i;
 
+	/* Recreate dc_state - DC invalidates it when setting power state to S3. */
+	dc_release_state(dm_state->context);
+	dm_state->context = dc_create_state(dm->dc);
+	/* TODO: Remove dc_state->dccg, use dc->dccg directly. */
+	dc_resource_state_construct(dm->dc, dm_state->context);
+
 	/* power on hardware */
 	dc_set_power_state(dm->dc, DC_ACPI_CM_POWER_STATE_D0);