diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index 252ac16635dce1f820c90ecb92c1609862fcaf25..28bee8d4473513748f65fed1893e92fe3c783d29 100644
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -923,6 +923,12 @@ struct usb_ptm_cap_descriptor {
 	__u8  bDevCapabilityType;
 } __attribute__((packed));
 
+/*
+ * The size of the descriptor for the Sublink Speed Attribute Count
+ * (SSAC) specified in bmAttributes[4:0].
+ */
+#define USB_DT_USB_SSP_CAP_SIZE(ssac)	(16 + ssac * 4)
+
 /*-------------------------------------------------------------------------*/
 
 /* USB_DT_WIRELESS_ENDPOINT_COMP:  companion descriptor associated with