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 <[EMAIL PROTECTED]>
---
--- 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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