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    Subject[PATCH 2/5] memstick: Prevent memstick host from getting runtime suspended during card detection
    Date
    We can use MEMSTICK_POWER_{ON,OFF} along with pm_runtime_{get,put}
    helpers to let memstick host support runtime pm.

    There's a small window between memstick_detect_change() and its queued
    work, memstick_check(). In this window the rpm count may go down to zero
    before the memstick host powers on, so the host can be inadvertently
    suspended.

    Increment rpm count before calling memstick_check(), and decrement rpm
    count afterward, as now we are sure the memstick host should be
    suspended or not.

    Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
    ---
    drivers/memstick/core/memstick.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
    index 76382c858c35..944fe0c93fa7 100644
    --- a/drivers/memstick/core/memstick.c
    +++ b/drivers/memstick/core/memstick.c
    @@ -18,6 +18,7 @@
    #include <linux/delay.h>
    #include <linux/slab.h>
    #include <linux/module.h>
    +#include <linux/pm_runtime.h>

    #define DRIVER_NAME "memstick"

    @@ -209,6 +210,7 @@ static int memstick_dummy_check(struct memstick_dev *card)
    */
    void memstick_detect_change(struct memstick_host *host)
    {
    + pm_runtime_get_noresume(host->dev.parent);
    queue_work(workqueue, &host->media_checker);
    }
    EXPORT_SYMBOL(memstick_detect_change);
    @@ -479,6 +481,8 @@ static void memstick_check(struct work_struct *work)
    host->set_param(host, MEMSTICK_POWER, MEMSTICK_POWER_OFF);

    mutex_unlock(&host->lock);
    +
    + pm_runtime_put_noidle(host->dev.parent);
    dev_dbg(&host->dev, "memstick_check finished\n");
    }

    --
    2.17.1
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