[PATCH 3/6] mmc: dw_mmc: convert card tasklet to workqueue

James Hogan
2011-06-24T13:12:17Z

Convert the card insert/remove tasklet to a workqueue, and call the
setpower platform specific callback without the spinlock held. This
means neither of the setpower or get_cd callbacks are called from atomic
context which allows them to sleep.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
drivers/mmc/host/dw_mmc.c | 50 +++++++++++++++++++++++++++----------------
include/linux/mmc/dw_mmc.h | 2 +-
2 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index c4bddf6..3f610d5 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -33,6 +33,7 @@
#include <linux/mmc/dw_mmc.h>
#include <linux/bitops.h>
#include <linux/regulator/consumer.h>
+#include <linux/workqueue.h>

#include "dw_mmc.h"

@@ -100,6 +101,8 @@ struct dw_mci_slot {
int last_detect_state;
};

+static struct workqueue_struct *dw_mci_card_workqueue;
+
#if defined(CONFIG_DEBUG_FS)
static int dw_mci_req_show(struct seq_file *s, void *v)
{
@@ -1255,7 +1258,7 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)

if (pending & SDMMC_INT_CD) {
mci_writel(host, RINTSTS, SDMMC_INT_CD);
- tasklet_schedule(&host->card_tasklet);
+ queue_work(dw_mci_card_workqueue, &host->card_work);
}

} while (pass_count++ < 5);
@@ -1274,9 +1277,9 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
return IRQ_HANDLED;
}

-static void dw_mci_tasklet_card(unsigned long data)
+static void dw_mci_work_routine_card(struct work_struct *work)
{
- struct dw_mci *host = (struct dw_mci *)data;
+ struct dw_mci *host = container_of(work, struct dw_mci, card_work);
int i;

for (i = 0; i < host->num_slots; i++) {
@@ -1288,22 +1291,21 @@ static void dw_mci_tasklet_card(unsigned long data)

present = dw_mci_get_cd(mmc);
while (present != slot->last_detect_state) {
- spin_lock(&host->lock);
-
dev_dbg(&slot->mmc->class_dev, "card %s\n",
present ? "inserted" : "removed");

+ /* Power up slot (before spin_lock, may sleep) */
+ if (present != 0 && host->pdata->setpower)
+ host->pdata->setpower(slot->id, mmc->ocr_avail);
+
+ spin_lock_bh(&host->lock);
+
/* Card change detected */
slot->last_detect_state = present;

- /* Power up slot */
- if (present != 0) {
- if (host->pdata->setpower)
- host->pdata->setpower(slot->id,
- mmc->ocr_avail);
-
+ /* Mark card as present if applicable */
+ if (present != 0)
set_bit(DW_MMC_CARD_PRESENT, &slot->flags);
- }

/* Clean up queue if present */
mrq = slot->mrq;
@@ -1353,8 +1355,6 @@ static void dw_mci_tasklet_card(unsigned long data)

/* Power down slot */
if (present == 0) {
- if (host->pdata->setpower)
- host->pdata->setpower(slot->id, 0);
clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);

/*
@@ -1376,7 +1376,12 @@ static void dw_mci_tasklet_card(unsigned long data)

}

- spin_unlock(&host->lock);
+ spin_unlock_bh(&host->lock);
+
+ /* Power down slot (after spin_unlock, may sleep) */
+ if (present == 0 && host->pdata->setpower)
+ host->pdata->setpower(slot->id, 0);
+
present = dw_mci_get_cd(mmc);
}

@@ -1476,7 +1481,7 @@ static int __init dw_mci_init_slot(struct dw_mci *host, unsigned int id)
* Card may have been plugged in prior to boot so we
* need to run the detect tasklet
*/
- tasklet_schedule(&host->card_tasklet);
+ queue_work(dw_mci_card_workqueue, &host->card_work);

return 0;
}
@@ -1665,12 +1670,15 @@ static int dw_mci_probe(struct platform_device *pdev)
mci_writel(host, CLKSRC, 0);

tasklet_init(&host->tasklet, dw_mci_tasklet_func, (unsigned long)host);
- tasklet_init(&host->card_tasklet,
- dw_mci_tasklet_card, (unsigned long)host);
+ dw_mci_card_workqueue = alloc_workqueue("dw-mci-card",
+ WQ_MEM_RECLAIM | WQ_NON_REENTRANT, 1);
+ if (!dw_mci_card_workqueue)
+ goto err_dmaunmap;
+ INIT_WORK(&host->card_work, dw_mci_work_routine_card);

ret = request_irq(irq, dw_mci_interrupt, 0, "dw-mci", host);
if (ret)
- goto err_dmaunmap;
+ goto err_workqueue;

platform_set_drvdata(pdev, host);

@@ -1714,6 +1722,9 @@ err_init_slot:
}
free_irq(irq, host);

+err_workqueue:
+ destroy_workqueue(dw_mci_card_workqueue);
+
err_dmaunmap:
if (host->use_dma && host->dma_ops->exit)
host->dma_ops->exit(host);
@@ -1753,6 +1764,7 @@ static int __exit dw_mci_remove(struct platform_device *pdev)
mci_writel(host, CLKSRC, 0);

free_irq(platform_get_irq(pdev, 0), host);
+ destroy_workqueue(dw_mci_card_workqueue);
dma_free_coherent(&pdev->dev, PAGE_SIZE, host->sg_cpu, host->sg_dma);

if (host->use_dma && host->dma_ops->exit)
diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
index 55d9909..dea4847 100644
--- a/include/linux/mmc/dw_mmc.h
+++ b/include/linux/mmc/dw_mmc.h
@@ -131,7 +131,7 @@ struct dw_mci {
u32 stop_cmdr;
u32 dir_status;
struct tasklet_struct tasklet;
- struct tasklet_struct card_tasklet;
+ struct work_struct card_work;
unsigned long pending_events;
unsigned long completed_events;
enum dw_mci_state state;
--
1.7.2.3