Hi Tejun,

On Fri, Dec 21, 2012 at 05:57:07PM -0800, Tejun Heo wrote:
> There's no need to test whether a (delayed) work item in pending
> before queueing, flushing or cancelling it.  Most uses are unnecessary
> and quite a few of them are buggy.
> 
> Remove unnecessary pending tests from wm97xx.  Instead of testing
> work_pending(), use the return value of queue_work() to decide whether
> to disable IRQ or not.
> 
> Only compile tested.
> 
> Signed-off-by: Tejun Heo <[email protected]>
> Cc: Mark Brown <[email protected]>
> Cc: Liam Girdwood <[email protected]>
> Cc: [email protected]
> Cc: Dmitry Torokhov <[email protected]>
> ---
> Please let me know how this patch should be routed.  I can take it
> through the workqueue tree if necessary.
> 
> Thanks.
> 
>  drivers/input/touchscreen/wm97xx-core.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/wm97xx-core.c 
> b/drivers/input/touchscreen/wm97xx-core.c
> index 5dbe73a..fd16c63 100644
> --- a/drivers/input/touchscreen/wm97xx-core.c
> +++ b/drivers/input/touchscreen/wm97xx-core.c
> @@ -363,10 +363,8 @@ static irqreturn_t wm97xx_pen_interrupt(int irq, void 
> *dev_id)
>  {
>       struct wm97xx *wm = dev_id;
>  
> -     if (!work_pending(&wm->pen_event_work)) {
> +     if (queue_work(wm->ts_workq, &wm->pen_event_work))
>               wm->mach_ops->irq_enable(wm, 0);
> -             queue_work(wm->ts_workq, &wm->pen_event_work);
> -     }
>  

This is not 100% equivalent transformation as now we schedule first and
disable IRQ later... Anyway, I think the driver shoudl be converted to
threaded IRQ instead. Mark, does the patch below make any sense to you?

Thanks.

-- 
Dmitry


Input: wm97xx - switch to using threaded IRQ

Instead of manually disabling and enabling interrupts and scheduling work to
access the device, let's use threaded oneshot interrupt handler. It simplifies
things.

Signed-off-by: Dmitry Torokhov <[email protected]>
---
 drivers/input/touchscreen/wm97xx-core.c |   42 +++++--------------------------
 include/linux/wm97xx.h                  |    1 -
 2 files changed, 7 insertions(+), 36 deletions(-)

diff --git a/drivers/input/touchscreen/wm97xx-core.c 
b/drivers/input/touchscreen/wm97xx-core.c
index 5dbe73a..bf5eddf 100644
--- a/drivers/input/touchscreen/wm97xx-core.c
+++ b/drivers/input/touchscreen/wm97xx-core.c
@@ -289,11 +289,12 @@ void wm97xx_set_suspend_mode(struct wm97xx *wm, u16 mode)
 EXPORT_SYMBOL_GPL(wm97xx_set_suspend_mode);
 
 /*
- * Handle a pen down interrupt.
+ * Codec PENDOWN irq handler
+ *
  */
-static void wm97xx_pen_irq_worker(struct work_struct *work)
+static irqreturn_t wm97xx_pen_interrupt(int irq, void *dev_id)
 {
-       struct wm97xx *wm = container_of(work, struct wm97xx, pen_event_work);
+       struct wm97xx *wm = dev_id;
        int pen_was_down = wm->pen_is_down;
 
        /* do we need to enable the touch panel reader */
@@ -347,27 +348,6 @@ static void wm97xx_pen_irq_worker(struct work_struct *work)
        if (!wm->pen_is_down && wm->mach_ops->acc_enabled)
                wm->mach_ops->acc_pen_up(wm);
 
-       wm->mach_ops->irq_enable(wm, 1);
-}
-
-/*
- * Codec PENDOWN irq handler
- *
- * We have to disable the codec interrupt in the handler because it
- * can take up to 1ms to clear the interrupt source. We schedule a task
- * in a work queue to do the actual interaction with the chip.  The
- * interrupt is then enabled again in the slow handler when the source
- * has been cleared.
- */
-static irqreturn_t wm97xx_pen_interrupt(int irq, void *dev_id)
-{
-       struct wm97xx *wm = dev_id;
-
-       if (!work_pending(&wm->pen_event_work)) {
-               wm->mach_ops->irq_enable(wm, 0);
-               queue_work(wm->ts_workq, &wm->pen_event_work);
-       }
-
        return IRQ_HANDLED;
 }
 
@@ -378,12 +358,9 @@ static int wm97xx_init_pen_irq(struct wm97xx *wm)
 {
        u16 reg;
 
-       /* If an interrupt is supplied an IRQ enable operation must also be
-        * provided. */
-       BUG_ON(!wm->mach_ops->irq_enable);
-
-       if (request_irq(wm->pen_irq, wm97xx_pen_interrupt, IRQF_SHARED,
-                       "wm97xx-pen", wm)) {
+       if (request_threaded_irq(wm->pen_irq, NULL, wm97xx_pen_interrupt,
+                                IRQF_SHARED | IRQF_ONESHOT,
+                                "wm97xx-pen", wm)) {
                dev_err(wm->dev,
                        "Failed to register pen down interrupt, polling");
                wm->pen_irq = 0;
@@ -502,7 +479,6 @@ static int wm97xx_ts_input_open(struct input_dev *idev)
        wm->codec->dig_enable(wm, 1);
 
        INIT_DELAYED_WORK(&wm->ts_reader, wm97xx_ts_reader);
-       INIT_WORK(&wm->pen_event_work, wm97xx_pen_irq_worker);
 
        wm->ts_reader_min_interval = HZ >= 100 ? HZ / 100 : 1;
        if (wm->ts_reader_min_interval < 1)
@@ -553,10 +529,6 @@ static void wm97xx_ts_input_close(struct input_dev *idev)
 
        wm->pen_is_down = 0;
 
-       /* Balance out interrupt disables/enables */
-       if (cancel_work_sync(&wm->pen_event_work))
-               wm->mach_ops->irq_enable(wm, 1);
-
        /* ts_reader rearms itself so we need to explicitly stop it
         * before we destroy the workqueue.
         */
diff --git a/include/linux/wm97xx.h b/include/linux/wm97xx.h
index fd98bb9..12f793d 100644
--- a/include/linux/wm97xx.h
+++ b/include/linux/wm97xx.h
@@ -280,7 +280,6 @@ struct wm97xx {
        unsigned long ts_reader_min_interval; /* Minimum interval */
        unsigned int pen_irq;           /* Pen IRQ number in use */
        struct workqueue_struct *ts_workq;
-       struct work_struct pen_event_work;
        u16 acc_slot;                   /* AC97 slot used for acc touch data */
        u16 acc_rate;                   /* acc touch data rate */
        unsigned pen_is_down:1;         /* Pen is down */
--
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