[patch 22/26] sis5513: fix PIO setup for ATAPI devices

[Greg KH]

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>

commit e13ee546bb06453939014c7b854e77fb643fd6f1 upstream.

Clear prefetch setting before potentially (re-)enabling it in
config_drive_art_rwp() so the transition of the device type on
the port from ATA to ATAPI (i.e. during warm-plug operation)
is handled correctly.

This is a really old bug (it probably goes back to very early
days of the driver) but it was only affecting warm-plug operation
until the recent "ide: try to use PIO Mode 0 during probe if
possible" change (commit 6029336426a2b43e4bc6f4a84be8789a047d139e).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
Tested-by: David Fries <david@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/ide/sis5513.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/ide/sis5513.c
+++ b/drivers/ide/sis5513.c
@@ -2,7 +2,7 @@
  * Copyright (C) 1999-2000	Andre Hedrick <andre@xxxxxxxxxxxxx>
  * Copyright (C) 2002		Lionel Bouton <Lionel.Bouton@xxxxxxxx>, Maintainer
  * Copyright (C) 2003		Vojtech Pavlik <vojtech@xxxxxxx>
- * Copyright (C) 2007		Bartlomiej Zolnierkiewicz
+ * Copyright (C) 2007-2009	Bartlomiej Zolnierkiewicz
  *
  * May be copied or modified under the terms of the GNU General Public License
  *
@@ -281,11 +281,13 @@ static void config_drive_art_rwp(ide_dri
 
 	pci_read_config_byte(dev, 0x4b, &reg4bh);
 
+	rw_prefetch = reg4bh & ~(0x11 << drive->dn);
+
 	if (drive->media == ide_disk)
-		rw_prefetch = 0x11 << drive->dn;
+		rw_prefetch |= 0x11 << drive->dn;
 
-	if ((reg4bh & (0x11 << drive->dn)) != rw_prefetch)
-		pci_write_config_byte(dev, 0x4b, reg4bh|rw_prefetch);
+	if (reg4bh != rw_prefetch)
+		pci_write_config_byte(dev, 0x4b, rw_prefetch);
 }
 
 static void sis_set_pio_mode(ide_drive_t *drive, const u8 pio)


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