diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index ad2f3b0d922f..c08368c03dad 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -447,6 +447,12 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
 	}
 }
 
+static union child_device_config *
+child_device_ptr(struct bdb_general_definitions *p_defs, int i)
+{
+	return (void *) &p_defs->devices[i * p_defs->child_dev_size];
+}
+
 static void
 parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
 			  struct bdb_header *bdb)
@@ -476,10 +482,10 @@ parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
 	block_size = get_blocksize(p_defs);
 	/* get the number of child device */
 	child_device_num = (block_size - sizeof(*p_defs)) /
-				sizeof(*p_child);
+		p_defs->child_dev_size;
 	count = 0;
 	for (i = 0; i < child_device_num; i++) {
-		p_child = &(p_defs->devices[i]);
+		p_child = child_device_ptr(p_defs, i);
 		if (!p_child->old.device_type) {
 			/* skip the device block if device type is invalid */
 			continue;
@@ -1067,25 +1073,19 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
 		DRM_DEBUG_KMS("No general definition block is found, no devices defined.\n");
 		return;
 	}
-	/* judge whether the size of child device meets the requirements.
-	 * If the child device size obtained from general definition block
-	 * is different with sizeof(struct child_device_config), skip the
-	 * parsing of sdvo device info
-	 */
-	if (p_defs->child_dev_size != sizeof(*p_child)) {
-		/* different child dev size . Ignore it */
-		DRM_DEBUG_KMS("different child size is found. Invalid.\n");
+	if (p_defs->child_dev_size < sizeof(*p_child)) {
+		DRM_ERROR("General definiton block child device size is too small.\n");
 		return;
 	}
 	/* get the block size of general definitions */
 	block_size = get_blocksize(p_defs);
 	/* get the number of child device */
 	child_device_num = (block_size - sizeof(*p_defs)) /
-				sizeof(*p_child);
+				p_defs->child_dev_size;
 	count = 0;
 	/* get the number of child device that is present */
 	for (i = 0; i < child_device_num; i++) {
-		p_child = &(p_defs->devices[i]);
+		p_child = child_device_ptr(p_defs, i);
 		if (!p_child->common.device_type) {
 			/* skip the device block if device type is invalid */
 			continue;
@@ -1105,7 +1105,7 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
 	dev_priv->vbt.child_dev_num = count;
 	count = 0;
 	for (i = 0; i < child_device_num; i++) {
-		p_child = &(p_defs->devices[i]);
+		p_child = child_device_ptr(p_defs, i);
 		if (!p_child->common.device_type) {
 			/* skip the device block if device type is invalid */
 			continue;
diff --git a/drivers/gpu/drm/i915/intel_bios.h b/drivers/gpu/drm/i915/intel_bios.h
index 6afd5be33367..af0b47652752 100644
--- a/drivers/gpu/drm/i915/intel_bios.h
+++ b/drivers/gpu/drm/i915/intel_bios.h
@@ -277,9 +277,9 @@ struct bdb_general_definitions {
 	 * And the device num is related with the size of general definition
 	 * block. It is obtained by using the following formula:
 	 * number = (block_size - sizeof(bdb_general_definitions))/
-	 *	     sizeof(child_device_config);
+	 *	     defs->child_dev_size;
 	 */
-	union child_device_config devices[0];
+	uint8_t devices[0];
 } __packed;
 
 /* Mask for DRRS / Panel Channel / SSC / BLT control bits extraction */