[PATCH 2.6.16.27] Fix broken suspend/resume in ohci1394

[Stefan Richter <stefanr@s5r6.in-berlin.de>]

Date: Mon, 22 May 2006 16:57:16 -0600
From: Robert Hancock <hancockr@shaw.ca>
Subject: Fix broken suspend/resume in ohci1394 (Was: ACPI suspend problems revisited)

I've been experimenting to track down the cause of suspend/resume problems
on my Compaq Presario X1050 laptop:

http://bugzilla.kernel.org/show_bug.cgi?id=6075

Essentially the ACPI Embedded Controller and keyboard controller would
get into a bizarre, confused state after resume.

I found that unloading the ohci1394 module before suspend and reloading it
after resume made the problem go away.  Diffing the dmesg output from
resume, with and without the module loaded, I found that with the module
loaded I was missing these:

PM: Writing back config space on device 0000:02:00.0 at offset 1. (Was 2100080, writing 2100007)
PM: Writing back config space on device 0000:02:00.0 at offset 3. (Was 0, writing 8008)
PM: Writing back config space on device 0000:02:00.0 at offset 4. (Was 0, writing 90200000)
PM: Writing back config space on device 0000:02:00.0 at offset 5. (Was 1, writing 2401)
PM: Writing back config space on device 0000:02:00.0 at offset f. (Was 20000100, writing 2000010a)

The default PCI driver performs the pci_restore_state when no driver is
loaded for the device.  When the ohci1394 driver is loaded, it is supposed
to do this, however it appears not to do so.

I created the patch below and tested it, and it appears to resolve the
suspend problems I was having with the module loaded.  I only added in the
pci_save_state and pci_restore_state - however, though I know little of
this hardware, surely the driver should really be doing more than this when
suspending and resuming?  Currently it does almost nothing, what if there
are commands in progress, etc?

Signed-off-by: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
This patch also appeared in 2.6.17.2 and 2.6.18.  There is still some
functionality missing for full resume capability in ohci1394.

Index: linux-2.6.16.27/drivers/ieee1394/ohci1394.c
===================================================================
--- linux-2.6.16.27.orig/drivers/ieee1394/ohci1394.c	2006-08-10 18:10:13.000000000 +0200
+++ linux-2.6.16.27/drivers/ieee1394/ohci1394.c	2006-08-10 18:11:45.000000000 +0200
@@ -3536,6 +3536,7 @@ static int ohci1394_pci_resume (struct p
 	}
 #endif /* CONFIG_PPC_PMAC */
 
+	pci_restore_state(pdev);
 	pci_enable_device(pdev);
 
 	return 0;
@@ -3555,6 +3556,8 @@ static int ohci1394_pci_suspend (struct 
 	}
 #endif
 
+	pci_save_state(pdev);
+
 	return 0;
 }