From 3e234af16e478c8ef6036e379256c9ed9bc7b7bf Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Thu, 6 May 2021 11:45:40 +0200
Subject: [PATCH] tape: improve inline docs for READ POSITION LONG

---
 src/tape/drive/lto/sg_tape.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/tape/drive/lto/sg_tape.rs b/src/tape/drive/lto/sg_tape.rs
index 46fc0982..6df69cb2 100644
--- a/src/tape/drive/lto/sg_tape.rs
+++ b/src/tape/drive/lto/sg_tape.rs
@@ -328,6 +328,9 @@ impl SgTape {
         let mut sg_raw = SgRaw::new(&mut self.file, 32)?;
         sg_raw.set_timeout(30); // use short timeout
         let mut cmd = Vec::new();
+        // READ POSITION LONG FORM works on LTO4 or newer (with recent
+        // firmware), although it is missing in the IBM LTO4 SSCI
+        // reference manual.
         cmd.extend(&[0x34, 0x06, 0, 0, 0, 0, 0, 0, 0, 0]); // READ POSITION LONG FORM
 
         let data = sg_raw.do_command(&cmd)