Re: [patch 2.6] don't put IDE disks in standby mode on halt on Alpha

[Ivan Kokshaysky <ink@jurassic.park.msu.ru>]

On Thu, May 27, 2004 at 07:40:49PM +0200, Bartlomiej Zolnierkiewicz wrote:
> > Would #ifdef __alpha__ be better?
> 
> actually CONFIG_ALPHA + comment why it is needed

Ok, but now I'm thinking of probably better solution:
consider sys_state == SYSTEM_HALT as another special case
where we put the disk into standby mode *only* if it does
have write cache but doesn't suppurt cache flush command
(or cache flush fails for some reason).

Hopefully, most drives won't be spun down on halt.
I think that it should be acceptable for x86 as well.

Ivan.

--- 2.6/drivers/ide/ide-disk.c	Fri May 28 17:46:35 2004
+++ linux/drivers/ide/ide-disk.c	Fri May 28 18:42:47 2004
@@ -1686,13 +1686,19 @@ static void idedisk_setup (ide_drive_t *
 #endif
 }
 
-static void ide_cacheflush_p(ide_drive_t *drive)
+static int ide_cacheflush_p(ide_drive_t *drive)
 {
-	if (!drive->wcache || !ide_id_has_flush_cache(drive->id))
-		return;
+	if (!drive->wcache)
+		return 0;
+
+	if (!ide_id_has_flush_cache(drive->id))
+		return 1;
 
-	if (do_idedisk_flushcache(drive))
-		printk(KERN_INFO "%s: wcache flush failed!\n", drive->name);
+	if (!do_idedisk_flushcache(drive))
+		return 0;
+
+	printk(KERN_INFO "%s: wcache flush failed!\n", drive->name);
+	return 1;
 }
 
 static int idedisk_cleanup (ide_drive_t *drive)
@@ -1713,10 +1719,16 @@ static void ide_device_shutdown(struct d
 {
 	ide_drive_t *drive = container_of(dev, ide_drive_t, gendev);
 
+	/* Never spin the disk down on reboot. */
 	if (system_state == SYSTEM_RESTART) {
 		ide_cacheflush_p(drive);
 		return;
 	}
+
+	/* Spin the disk down on halt only if attempt to flush the
+	   write cache fails. */
+	if (system_state == SYSTEM_HALT && !ide_cacheflush_p(drive))
+		return;
 
 	printk("Shutdown: %s\n", drive->name);
 	dev->bus->suspend(dev, PM_SUSPEND_STANDBY);