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SubjectRe: [PATCH 17/25] wm97xx: don't use [delayed_]work_pending()
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 <tj@kernel.org>
> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
> Cc: Liam Girdwood <lrg@slimlogic.co.uk>
> Cc: linux-input@vger.kernel.org
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
> 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 <dmitry.torokhov@gmail.com>
---
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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