[PATCH] libata: fix translation for START STOP UNIT

[Robert Hancock <hancockr@shaw.ca>]

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Applies to 2.6.20-rc6.

---

libata's SCSI translation for the SCSI START STOP UNIT command with the 
START bit clear (i.e. stopping the drive) appears to be incorrect. It 
sends an ATA STANDBY command with the time period set to 0, which the 
code comment says means "now", but the ATA standard says this means 
disable the standby timer, which effectively does nothing. Change this 
to issue a STANDBY IMMEDIATE command which will actually spin the drive 
down. The SAT (SCSI/ATA Translation) standard revision 9 concurs with 
this choice.

Signed-off-by: Robert Hancock <hancockr@shaw.ca>

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/



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--- linux-2.6.20-rc6nv/drivers/ata/libata-scsi.c	2007-01-28 16:59:58.000000000 -0600
+++ linux-2.6.20-rc6nvedit/drivers/ata/libata-scsi.c	2007-01-28 17:30:12.000000000 -0600
@@ -983,11 +983,10 @@ static unsigned int ata_scsi_start_stop_
 		}
 
 		tf->command = ATA_CMD_VERIFY;	/* READ VERIFY */
-	} else {
-		tf->nsect = 0;	/* time period value (0 implies now) */
-		tf->command = ATA_CMD_STANDBY;
-		/* Consider: ATA STANDBY IMMEDIATE command */
-	}
+	} else
+		/* Issue ATA STANDBY IMMEDIATE command */
+		tf->command = ATA_CMD_STANDBYNOW1;
+
 	/*
 	 * Standby and Idle condition timers could be implemented but that
 	 * would require libata to implement the Power condition mode page