From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Subject: [PATCH] Revert "Revert "ide: try to use PIO Mode 0 during probe if possible""

This reverts commit 24df31acaff8465d797f0006437b45ad0f2a5cb1.

The root cause of reported system hangs was (now fixed) sis5513 bug
and not "ide: try to use PIO Mode 0 during probe if possible" change
(commit 6029336426a2b43e4bc6f4a84be8789a047d139e) so the revert was
incorrect (it simply replaced one regression with the other one).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Joao Ramos <joao.ramos@inov.pt>
Cc: David Fries <david@fries.net>
Cc: d.stussy@yahoo.com
---
 drivers/ide/ide-probe.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index 4d76ba4..63c53d6 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -1046,6 +1046,15 @@ static void ide_port_init_devices(ide_hwif_t *hwif)
 		if (port_ops && port_ops->init_dev)
 			port_ops->init_dev(drive);
 	}
+
+	ide_port_for_each_dev(i, drive, hwif) {
+		/*
+		 * default to PIO Mode 0 before we figure out
+		 * the most suited mode for the attached device
+		 */
+		if (port_ops && port_ops->set_pio_mode)
+			port_ops->set_pio_mode(drive, 0);
+	}
 }
 
 static void ide_init_port(ide_hwif_t *hwif, unsigned int port,
-- 
1.6.5.rc2

--

[ message continues ]

From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

What is this older "regression" fixed by the PIO-0 change?

You're not explaining it and neither does the commit message for the
PIO-0 change.

Please, fill us in :-)
--

[ message continues ]

It does:

| Subject: [PATCH] sis5513: fix PIO setup for ATAPI devices
| 
| 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.


Just connect the dots.. :)
--

[ message continues ]

From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Sorry, I wasn't clear.

I'm talking about commit 6029336426a2b43e4bc6f4a84be8789a047d139e, it
doesn't say why we want to try PIO 0 mode during probe.

What was the regression fixed by that change?

--

[ message continues ]

For the same reason that libata wants it.

Many embedded controllers/platforms will have junk PIO timings set initially.

Now that your manager's ambition is satisfied could you please go help
some other subsystem for the moment so we can fix ide in the meantime? :)
--

[ message continues ]

From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Thanks, that helps a lot.

When David reports back on testing I'll push this stuff around
and queue up patch #1 for -stable.
--

[ message continues ]