[PATCH] 2.2.18pre21 ide-disk.c for OB800

[Grant Grundler]

hi folks,
I've been playing with hdparms on the OB800 (running debian 2.2 -
that 2.2.18pre21 based) as shown on:

	http://www.phys.unsw.edu.au/~mcba/hp800ct.html

The appended patch attemps to fix the following errors seen when the IDE
drive spins up after a sleep mode:
	hda: multwrite_intr: status=0x51 { DriveReady SeekComplete Error }
	hda: multwrite_intr: error=0x04 { DriveStatusError }
*or*
	hda: read_intr: status=0x59 { DriveReady SeekComplete DataReady Error }
	hda: read_intr: error=0x04 { DriveStatusError }

After several retries, both result in "ide0: reset: success" and life
is good again. The patch avoids the reset.

I have two theories on what's wrong: drive forgets multmode was enabled
*or* drive doesn't spin up media when poked. The web page above claims
the drive forgets the hdparm -S (idle time before sleep) and provides a
script to reset that. I've wondered if the same might be true for Multi-sector
mode. Anyway, resetting MultMode seems to fix the problem.

I've learned the drive will spin down in four different cases:
1) hdparm -S10 (50 seconds) and let the machine idle that long
2) BIOS APM has been idle and decides it time to sleep (I have
   mine set to 3 minutes right now)
3) "on/off" button on keyboard
4) hdparm -Y /dev/hda  (this case still generates similar errors.)

This patch does NOT fix another symptom:
o "irq timeout: status=0xd0 { Busy }" followed by "ide0: reset: success".

enjoy!
grant

grundler at puffin.external.hp.com
parisc-linux I/O hacker

--- kernel-source-2.2.18pre21-2.2.18pre21.ORIG/drivers/block/ide-disk.c	Wed Jun  7 14:26:42 2000
+++ linux/drivers/block/ide-disk.c	Wed Jan 10 15:03:15 2001
@@ -123,6 +123,23 @@ static int lba_capacity_is_ok (struct hd
 }
 
 /*
+ * set_multmode_intr() is invoked on completion of a WIN_SETMULT cmd.
+ */
+static ide_startstop_t set_multmode_intr (ide_drive_t *drive)
+{
+	byte stat = GET_STAT();
+
+	if (OK_STAT(stat,READY_STAT,BAD_STAT)) {
+		drive->mult_count = drive->mult_req;
+	} else {
+		drive->mult_req = drive->mult_count = 0;
+		drive->special.b.recalibrate = 1;
+		(void) ide_dump_status(drive, "set_multmode", stat);
+	}
+	return ide_stopped;
+}
+
+/*
  * read_intr() is the handler for disk read/multread interrupts
  */
 static ide_startstop_t read_intr (ide_drive_t *drive)
@@ -145,6 +162,32 @@ static ide_startstop_t read_intr (ide_dr
 		return ide_started;
 	}
 #endif
+	else if ((0x59 == stat) && drive->mult_count) {
+		/*
+		** HP OB800 laptop HD (IBM-DMCA-21440) will spin down
+		** and *forget* multi-mode parms when it spins up on
+		** the next access. The following fixes the stat 0x51
+		** w/error 0x4 messages and reset after spinning up.
+		** ggg 9.1.2001
+		**
+		** If first request which triggers resume is a write,
+		**  stat == 0x51 (vs. 0x59 for read).
+		**
+		** 1) Check if HD forgot.
+		** 2) If so, set them again, otherwise report error.
+		** 3) I/O is still queued - will get retried (I hope).
+		**
+		** REVISIT: Don't know how to easily check HD settings.
+		**    Not sure it's possible since it doesn't just seem to
+		**    be a simple register read. Not checking HD settings
+		**    risks an infinite loop/wedged system. I would expect
+		**    to get a different error for the SETMULT cmd.
+		*/
+		{
+			ide_cmd(drive, WIN_SETMULT, drive->mult_req, &set_multmode_intr);
+			return ide_started;
+		}
+	}
 	msect = drive->mult_count;
 	
 read_next:
@@ -331,24 +374,17 @@ static ide_startstop_t multwrite_intr (i
 		}
 		return ide_stopped;     /* the original code did this here (?) */ 
 	}
-	return ide_error(drive, "multwrite_intr", stat);
-}
-
-/*
- * set_multmode_intr() is invoked on completion of a WIN_SETMULT cmd.
- */
-static ide_startstop_t set_multmode_intr (ide_drive_t *drive)
-{
-	byte stat = GET_STAT();
-
-	if (OK_STAT(stat,READY_STAT,BAD_STAT)) {
-		drive->mult_count = drive->mult_req;
-	} else {
-		drive->mult_req = drive->mult_count = 0;
-		drive->special.b.recalibrate = 1;
-		(void) ide_dump_status(drive, "set_multmode", stat);
+	else if (0x51 == stat) {
+		/*
+		** HP OB800 laptop HD (IBM-DMCA-21440) fix.
+		** See comments in read_intr().
+		*/
+		{
+			ide_cmd(drive, WIN_SETMULT, drive->mult_req, &set_multmode_intr);
+			return ide_started;
+		}
 	}
-	return ide_stopped;
+	return ide_error(drive, "multwrite_intr", stat);
 }
 
 /*