[PATCH 14/18] MMC: OMAP: Use tasklet instead of workqueue for cover switch notification

Carlos Aguiar
2008-03-26T20:17:10Z

From: Jarkko Lavinen <jarkko.lavinen@nokia.com>

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>
---
drivers/mmc/host/omap.c | 67 ++++++++++++++++++++++++++++-------------------
1 files changed, 40 insertions(+), 27 deletions(-)

diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
index 0e7ceb0..f97f390 100644
--- a/drivers/mmc/host/omap.c
+++ b/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);
-- 1.5.3.GIT