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



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