From 4c7351ec7d55852b48cd816ed1e0d899e6283262 Mon Sep 17 00:00:00 2001
From: pk <pk@NetBSD.org>
Date: Fri, 3 Nov 2000 10:46:18 +0000
Subject: [PATCH] * st_touch_tape(): start probing at the block size from the
 sense data if   we have it.

* st_unmount(): reset density to the device default. This prevents using
  stale density values after changing to a medium with different density.

  Section 9.3.3 of the SCSI specs states that a device shall return the
  density value specified in the last succesfull MODE SELECT after an
  unload operation, in case it is not able to automatically determine
  the density of the new medium.
---
 sys/dev/scsipi/st.c | 52 +++++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 13 deletions(-)

diff --git a/sys/dev/scsipi/st.c b/sys/dev/scsipi/st.c
index 8cbb89964f3e..764bb022a61f 100644
--- a/sys/dev/scsipi/st.c
+++ b/sys/dev/scsipi/st.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: st.c,v 1.130 2000/11/03 10:22:02 pk Exp $ */
+/*	$NetBSD: st.c,v 1.131 2000/11/03 10:46:18 pk Exp $ */
 
 /*-
  * Copyright (c) 1998 The NetBSD Foundation, Inc.
@@ -249,7 +249,7 @@ struct st_quirk_inquiry_pattern st_quirk_patterns[] = {
 		{0, 0, 0}				/* minor 12-15 */
 	}}},
 	{{T_SEQUENTIAL, T_REMOV,
-	 "STK",      "9490",             ""},    
+	 "STK",      "9490",             ""},
 				{ST_Q_FORCE_BLKSIZE, 0, {
 		{0, 0, 0},				/* minor 0-3 */
 		{0, 0, 0},				/* minor 4-7 */
@@ -700,7 +700,7 @@ stopen(dev, flags, mode, p)
 		if (slpintr) {
 			goto bad;
 		}
-	} 
+	}
 
 
 	/*
@@ -825,7 +825,7 @@ stclose(dev, flags, mode, p)
 			 *	operation a write?
 			 *
 			 *	Are there supposed to be 2FM at EOD?
-			 *	
+			 *
 			 * If both statements are true, then we backspace
 			 * one filemark.
 			 */
@@ -969,6 +969,23 @@ st_unmount(st, eject)
 	SC_DEBUG(sc_link, SDEV_DB1, ("unmounting\n"));
 	st_check_eod(st, FALSE, &nmarks, XS_CTL_IGNORE_NOT_READY);
 	st_rewind(st, 0, XS_CTL_IGNORE_NOT_READY);
+
+	/*
+	 * Section 9.3.3 of the SCSI specs states that a device shall return
+	 * the density value specified in the last succesfull MODE SELECT
+	 * after an unload operation, in case it is not able to
+	 * automatically determine the density of the new medium.
+	 *
+	 * So we instruct the device to use the default density, which will
+	 * prevent the use of stale density values (in particular,
+	 * in st_touch_tape().
+	 */
+	st->density = 0;
+	if (st_mode_select(st, 0) != 0) {
+		printf("%s: WARNING: cannot revert to default density\n",
+			st->sc_dev.dv_xname);
+	}
+
 	scsipi_prevent(sc_link, PR_ALLOW,
 	    XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
 	if (eject)
@@ -1253,7 +1270,7 @@ ststart(v)
 		}
 		/*
 		 * If we are at EOM but have not reported it
-		 * yet then we should report it now. 
+		 * yet then we should report it now.
 		 */
 		if (st->flags & (ST_EOM_PENDING|ST_EIO_PENDING)) {
 			bp->b_resid = bp->b_bcount;
@@ -1833,7 +1850,7 @@ st_cmprss(st, onoff)
 again:
 	bzero(&scsi_pdata, scsi_dlen);
 	error = scsipi_command(sc_link,
-	    (struct scsipi_generic *)&scmd, sizeof(scmd), 
+	    (struct scsipi_generic *)&scmd, sizeof(scmd),
 	    (u_char *)&scsi_pdata, scsi_dlen,
 	    ST_RETRIES, ST_CTL_TIME, NULL,
 	    flags | XS_CTL_DATA_IN | XS_CTL_DATA_ONSTACK);
@@ -2484,7 +2501,7 @@ st_interpret_sense(xs)
 		xs->sc_link->sc_print_addr(xs->sc_link);
 		printf("Sense Key 0x%02x", key);
 		if ((sense->error_code & SSD_ERRCODE_VALID) != 0) {
-			switch (key) { 
+			switch (key) {
 			case SKEY_NOT_READY:
 			case SKEY_ILLEGAL_REQUEST:
 			case SKEY_UNIT_ATTENTION:
@@ -2492,7 +2509,7 @@ st_interpret_sense(xs)
 				break;
 			case SKEY_BLANK_CHECK:
 				printf(", requested size: %d (decimal)", info);
-				break; 
+				break;
 			case SKEY_ABORTED_COMMAND:
 				if (xs->retries)
 					printf(", retrying");
@@ -2502,13 +2519,13 @@ st_interpret_sense(xs)
 			default:
 				printf(", info = %d (decimal)", info);
 			}
-		} 
+		}
 		if (sense->extra_len != 0) {
-			int n; 
-			printf(", data ="); 
+			int n;
+			printf(", data =");
 			for (n = 0; n < sense->extra_len; n++)
 				printf(" %02x", sense->cmd_spec_info[n]);
-		} 
+		}
 		printf("\n");
 #endif
 	}
@@ -2545,7 +2562,16 @@ st_touch_tape(st)
 
 	if ((error = st_mode_sense(st, 0)) != 0)
 		goto bad;
-	st->blksize = 1024;
+
+	/*
+	 * If the block size is already known from the
+	 * sense data, use it. Else start probing at 1024.
+	 */
+	if (st->media_blksize > 0)
+		st->blksize = st->media_blksize;
+	else
+		st->blksize = 1024;
+
 	do {
 		switch (st->blksize) {
 		case 512: