MMC: OMAP: Use tasklet instead of workqueue for cover switch notification

The cover waitqueue is occasionally scheduled twice from timer
and the interrupt and oops follows. It would have been possible
to fix this problem with spinlocks but using tasklet was a dropin
solution with no need for locking.

This path also adds some cleanups.
Signed-off-by: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/host/omap.c

@@ -94,7 +94,7 @@
 
 /* Specifies how often in millisecs to poll for card status changes
  * when the cover switch is open */
-#define OMAP_MMC_SWITCH_POLL_DELAY	500
+#define OMAP_MMC_COVER_POLL_DELAY	500
 
 struct mmc_omap_host;
 
@@ -106,8 +106,8 @@ struct mmc_omap_slot {
 	unsigned int		fclk_freq;
 	unsigned		powered:1;
 
-	struct work_struct      switch_work;
-	struct timer_list       switch_timer;
+	struct tasklet_struct	cover_tasklet;
+	struct timer_list       cover_timer;
 	unsigned		cover_open;
 
 	struct mmc_request      *mrq;
@@ -740,40 +740,51 @@ static irqreturn_t mmc_omap_irq(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-void omap_mmc_notify_cover_event(struct device *dev, int slot, int is_closed)
+void omap_mmc_notify_cover_event(struct device *dev, int num, int is_closed)
 {
+	int cover_open;
 	struct mmc_omap_host *host = dev_get_drvdata(dev);
+	struct mmc_omap_slot *slot = host->slots[num];
 
-	BUG_ON(slot >= host->nr_slots);
+	BUG_ON(num >= host->nr_slots);
 
 	/* Other subsystems can call in here before we're initialised. */
-	if (host->nr_slots == 0 || !host->slots[slot])
+	if (host->nr_slots == 0 || !host->slots[num])
 		return;
 
-	schedule_work(&host->slots[slot]->switch_work);
+	cover_open = mmc_omap_cover_is_open(slot);
+	if (cover_open != slot->cover_open) {
+		slot->cover_open = cover_open;
+		sysfs_notify(&slot->mmc->class_dev.kobj, NULL, "cover_switch");
+	}
+
+	tasklet_hi_schedule(&slot->cover_tasklet);
 }
 
-static void mmc_omap_switch_timer(unsigned long arg)
+static void mmc_omap_cover_timer(unsigned long arg)
 {
 	struct mmc_omap_slot *slot = (struct mmc_omap_slot *) arg;
-
-	schedule_work(&slot->switch_work);
+	tasklet_schedule(&slot->cover_tasklet);
 }
 
-static void mmc_omap_cover_handler(struct work_struct *work)
+static void mmc_omap_cover_handler(unsigned long param)
 {
-	struct mmc_omap_slot *slot = container_of(work, struct mmc_omap_slot,
-						  switch_work);
-	int cover_open;
+	struct mmc_omap_slot *slot = (struct mmc_omap_slot *)param;
+	int cover_open = mmc_omap_cover_is_open(slot);
 
-	cover_open = mmc_omap_cover_is_open(slot);
-	if (cover_open != slot->cover_open) {
-		sysfs_notify(&slot->mmc->class_dev.kobj, NULL, "cover_switch");
-		slot->cover_open = cover_open;
-		dev_info(mmc_dev(slot->mmc), "cover is now %s\n",
-			 cover_open ? "open" : "closed");
-	}
-	mmc_detect_change(slot->mmc, slot->id);
+	mmc_detect_change(slot->mmc, 0);
+	if (!cover_open)
+		return;
+
+	/*
+	 * If no card is inserted, we postpone polling until
+	 * the cover has been closed.
+	 */
+	if (slot->mmc->card == NULL || !mmc_card_present(slot->mmc->card))
+		return;
+
+	mod_timer(&slot->cover_timer,
+		  jiffies + msecs_to_jiffies(OMAP_MMC_COVER_POLL_DELAY));
 }
 
 /* Prepare to transfer the next segment of a scatterlist */
@@ -1237,10 +1248,11 @@ static int __init mmc_omap_new_slot(struct mmc_omap_host *host, int id)
 		if (r < 0)
 			goto err_remove_slot_name;
 
-		INIT_WORK(&slot->switch_work, mmc_omap_cover_handler);
-		setup_timer(&slot->switch_timer, mmc_omap_switch_timer,
-			    (unsigned long) slot);
-		schedule_work(&slot->switch_work);
+		setup_timer(&slot->cover_timer, mmc_omap_cover_timer,
+			    (unsigned long)slot);
+		tasklet_init(&slot->cover_tasklet, mmc_omap_cover_handler,
+			     (unsigned long)slot);
+		tasklet_schedule(&slot->cover_tasklet);
 	}
 
 	return 0;
@@ -1263,7 +1275,8 @@ static void mmc_omap_remove_slot(struct mmc_omap_slot *slot)
 	if (slot->pdata->get_cover_state != NULL)
 		device_remove_file(&mmc->class_dev, &dev_attr_cover_switch);
 
-	del_timer_sync(&slot->switch_timer);
+	tasklet_kill(&slot->cover_tasklet);
+	del_timer_sync(&slot->cover_timer);
 	flush_scheduled_work();
 
 	mmc_remove_host(mmc);