Re: Loud "pop" coming from hard drive on reboot

[Stephen Clark <Stephen.Clark@seclark.us>]

Mark Lord wrote:

>Alan Cox wrote:
>  
>
>>>+		if (dev->needs_flush && ata_try_flush_cache(dev)) {
>>> 			return ata_scsi_flush_xlat;
>>>+			dev->needs_flush = 0;
>>>      
>>>
>>Works better if you swap the dev-> and return lines
>>    
>>
>
>Heh, yeah, I noticed that!
>
>Here it is, *tested* now, with another fix.
>
>It would be nice if somebody who can hear the "pop" would also test this,
>as it will confirm that this is a complete fix for the problem.
>My "pop" drives are busy elsewhere right now.
>
>Tejun might use something like this, or do something better in libata-core,
>but it's still helpful to have confirmation that we're on the right track.
>
>This patch eliminates the redundant "SYNCHRONIZE_CACHE" request at shutdown
>which is causing undue wear/tear/alarm to various systems.
>
>Signed-off-by: Mark Lord <mlord@pobox.com>
>---
>--- old/include/linux/libata.h	2007-04-18 10:30:25.000000000 -0400
>+++ linux/include/linux/libata.h	2007-04-18 10:30:28.000000000 -0400
>@@ -499,6 +499,7 @@
> 	struct ata_ering	ering;
> 	int			spdn_cnt;
> 	unsigned int		horkage;	/* List of broken features */
>+	int			needs_sync_cache; /* 0==sync-cache not needed */
> #ifdef CONFIG_SATA_ACPI
> 	/* ACPI objects info */
> 	acpi_handle obj_handle;
>--- old/drivers/ata/libata-scsi.c	2007-04-18 10:48:34.000000000 -0400
>+++ linux/drivers/ata/libata-scsi.c	2007-04-18 10:51:09.000000000 -0400
>@@ -2749,18 +2749,20 @@
> 			return atapi_xlat;
> 
> 	switch (cmd) {
>-	case READ_6:
>-	case READ_10:
>-	case READ_16:
>-
> 	case WRITE_6:
> 	case WRITE_10:
> 	case WRITE_16:
>+		dev->needs_sync_cache = 1;
>+	case READ_6:
>+	case READ_10:
>+	case READ_16:
> 		return ata_scsi_rw_xlat;
> 
> 	case SYNCHRONIZE_CACHE:
>-		if (ata_try_flush_cache(dev))
>+		if (dev->needs_sync_cache && ata_try_flush_cache(dev)) {
>+			dev->needs_sync_cache = 0;
> 			return ata_scsi_flush_xlat;
>+		}
> 		break;
> 
> 	case VERIFY:
>@@ -2769,6 +2771,7 @@
> 
> 	case ATA_12:
> 	case ATA_16:
>+		dev->needs_sync_cache = 1;
> 		return ata_scsi_pass_thru;
> 
> 	case START_STOP:
>-
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>
>  
>
I tried this on 2.6.20.2 it applied to libata with some fuzz and I had 
to manually edit libata.h
When I did a shutdown I still got the click/pop.

I also noticed the last thing displayed on the lcd before it goes blank is
Synchronizing SCSI Disks - then the click/pop.

HTH,
Steve

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