From 2a66443a495c687e7a46724099d2d9aeb0b83f97 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Fri, 9 Feb 2024 13:02:05 -0500
Subject: [PATCH] Add DoorbellRegister comment

---
 src/hulk/usb/xhci.d | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/hulk/usb/xhci.d b/src/hulk/usb/xhci.d
index 3323ed4..d23f8e1 100644
--- a/src/hulk/usb/xhci.d
+++ b/src/hulk/usb/xhci.d
@@ -35,6 +35,7 @@ struct XHCI
         ushort hci_version;
 
         /**
+         * HCSPARAMS1.
          * 7:0 number of device slots (MaxSlots)
          * 18:8 number of interrupters (MaxIntrs)
          * 23:19 reserved
@@ -320,6 +321,12 @@ struct XHCI
         ulong erdp;
     }
 
+    /**
+     * Located at offset doorbell_offset from PCI base address.
+     *
+     * The number of these is given by HCSPARAMS1.MaxSlots + 1 (for the command
+     * ring).
+     */
     struct DoorbellRegister
     {
         ubyte target;