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[6/6] mtd: maps: sa1100-flash: Add reference counter to set_vpp()

Message ID 1331129671.42251.YahooMailClassic@web29005.mail.ird.yahoo.com
State Accepted
Commit ee478af8b675908b217198a75cf759d422a81ccb
Headers show

Commit Message

Paul Parsons March 7, 2012, 2:14 p.m. UTC 
This patch is part of a set which fixes unnecessary flash erase and write errors
resulting from the MTD CFI driver turning off vpp while an erase is in progress.
This patch allows sa1100_set_vpp() calls to be nested by adding a reference
counter.

Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
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Patch

diff -uprN clean-3.3-rc6/drivers/mtd/maps/sa1100-flash.c linux-3.3-rc6/drivers/mtd/maps/sa1100-flash.c
--- clean-3.3-rc6/drivers/mtd/maps/sa1100-flash.c	2012-03-04 01:08:09.000000000 +0000
+++ linux-3.3-rc6/drivers/mtd/maps/sa1100-flash.c	2012-03-06 16:38:29.795134347 +0000
@@ -136,10 +136,22 @@  struct sa_info {
 	struct sa_subdev_info	subdev[0];
 };
 
+static DEFINE_SPINLOCK(sa1100_vpp_lock);
+static int sa1100_vpp_refcnt;
 static void sa1100_set_vpp(struct map_info *map, int on)
 {
 	struct sa_subdev_info *subdev = container_of(map, struct sa_subdev_info, map);
-	subdev->plat->set_vpp(on);
+	unsigned long flags;
+
+	spin_lock_irqsave(&sa1100_vpp_lock, flags);
+	if (on) {
+		if (++sa1100_vpp_refcnt == 1)   /* first nested 'on' */
+			subdev->plat->set_vpp(1);
+	} else {
+		if (--sa1100_vpp_refcnt == 0)   /* last nested 'off' */
+			subdev->plat->set_vpp(0);
+	}
+	spin_unlock_irqrestore(&sa1100_vpp_lock, flags);
 }
 
 static void sa1100_destroy_subdev(struct sa_subdev_info *subdev)