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Message-ID: <20090714044957.GD2822@dtor-d630.eng.vmware.com>
Date: Mon, 13 Jul 2009 21:59:29 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Richard Röjfors
<richard.rojfors.ext@...ean-labs.com>
Cc: linux-input@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
kwangwoo.lee@...il.com,
Thierry Reding <thierry.reding@...onic-design.de>,
Trilok Soni <soni.trilok@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] tsc2007: remove HR timer
Hi Richard,
On Tue, Jun 23, 2009 at 01:54:48PM +0200, Richard Röjfors wrote:
> This patch removes the HR timer, since it's bad to do synchronous I2C
> in the HR timer callback context. The new implementation makes use
> of the global workqueue. The work is scheduled every 5ms when polling
> rather than 5 us.
>
> Signed-off-by: Richard Röjfors <richard.rojfors.ext@...ean-labs.com>
> ---
> Index: linux-2.6.30/drivers/input/touchscreen/tsc2007.c
> ===================================================================
> --- linux-2.6.30/drivers/input/touchscreen/tsc2007.c (revision 932)
> +++ linux-2.6.30/drivers/input/touchscreen/tsc2007.c (revision 943)
> @@ -21,15 +21,13 @@
> */
>
> #include <linux/module.h>
> -#include <linux/hrtimer.h>
> #include <linux/slab.h>
> #include <linux/input.h>
> #include <linux/interrupt.h>
> #include <linux/i2c.h>
> #include <linux/i2c/tsc2007.h>
>
> -#define TS_POLL_DELAY (10 * 1000) /* ns delay before the first sample */
> -#define TS_POLL_PERIOD (5 * 1000) /* ns delay between samples */
> +#define TS_POLL_PERIOD msecs_to_jiffies(5) /* ms delay between samples */
>
> #define TSC2007_MEASURE_TEMP0 (0x0 << 4)
> #define TSC2007_MEASURE_AUX (0x2 << 4)
> @@ -70,13 +68,11 @@
> struct tsc2007 {
> struct input_dev *input;
> char phys[32];
> - struct hrtimer timer;
> + struct delayed_work work;
> struct ts_event tc;
>
> struct i2c_client *client;
>
> - spinlock_t lock;
> -
> u16 model;
> u16 x_plate_ohms;
>
> @@ -142,8 +138,7 @@
> if (rt > MAX_12BIT) {
> dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
>
> - hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
> - HRTIMER_MODE_REL);
> + schedule_delayed_work(&ts->work, TS_POLL_PERIOD);
> return;
> }
>
> @@ -153,7 +148,7 @@
> * in some cases may not even settle at the expected value.
> *
> * The only safe way to check for the pen up condition is in the
> - * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
> + * work function by reading the pen signal state (it's a GPIO and IRQ).
> */
> if (rt) {
> struct input_dev *input = ts->input;
> @@ -175,8 +170,7 @@
> x, y, rt);
> }
>
> - hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_PERIOD),
> - HRTIMER_MODE_REL);
> + schedule_delayed_work(&ts->work, TS_POLL_PERIOD);
> }
>
> static int tsc2007_read_values(struct tsc2007 *tsc)
> @@ -197,13 +191,10 @@
> return 0;
> }
>
> -static enum hrtimer_restart tsc2007_timer(struct hrtimer *handle)
> +static void tsc2007_work(struct work_struct *work)
> {
> - struct tsc2007 *ts = container_of(handle, struct tsc2007, timer);
> - unsigned long flags;
> -
> - spin_lock_irqsave(&ts->lock, flags);
> -
> + struct tsc2007 *ts =
> + container_of(to_delayed_work(work), struct tsc2007, work);
> if (unlikely(!ts->get_pendown_state() && ts->pendown)) {
> struct input_dev *input = ts->input;
>
> @@ -222,30 +213,20 @@
> tsc2007_read_values(ts);
> tsc2007_send_event(ts);
> }
> -
> - spin_unlock_irqrestore(&ts->lock, flags);
> -
> - return HRTIMER_NORESTART;
> }
>
> static irqreturn_t tsc2007_irq(int irq, void *handle)
> {
> struct tsc2007 *ts = handle;
> - unsigned long flags;
>
> - spin_lock_irqsave(&ts->lock, flags);
> -
> if (likely(ts->get_pendown_state())) {
> disable_irq_nosync(ts->irq);
> - hrtimer_start(&ts->timer, ktime_set(0, TS_POLL_DELAY),
> - HRTIMER_MODE_REL);
> + schedule_delayed_work(&ts->work, 0);
Originally we scheduled reading with timy delay to let the device
settle, why don't we schedule with 1ms delay?
> }
>
> if (ts->clear_penirq)
> ts->clear_penirq();
>
> - spin_unlock_irqrestore(&ts->lock, flags);
> -
> return IRQ_HANDLED;
> }
>
> @@ -278,11 +259,6 @@
>
> ts->input = input_dev;
>
> - hrtimer_init(&ts->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> - ts->timer.function = tsc2007_timer;
> -
> - spin_lock_init(&ts->lock);
> -
> ts->model = pdata->model;
> ts->x_plate_ohms = pdata->x_plate_ohms;
> ts->get_pendown_state = pdata->get_pendown_state;
> @@ -308,6 +284,8 @@
>
> ts->irq = client->irq;
>
> + INIT_DELAYED_WORK(&ts->work, tsc2007_work);
> +
> err = request_irq(ts->irq, tsc2007_irq, 0,
> client->dev.driver->name, ts);
> if (err < 0) {
> @@ -325,7 +303,6 @@
>
> err_free_irq:
> free_irq(ts->irq, ts);
> - hrtimer_cancel(&ts->timer);
Why don't we cancel work here?
> err_free_mem:
> input_free_device(input_dev);
> kfree(ts);
> @@ -337,11 +314,13 @@
> struct tsc2007 *ts = i2c_get_clientdata(client);
> struct tsc2007_platform_data *pdata;
>
> + /* cancel any work */
> + cancel_delayed_work(&ts->work);
> +
> pdata = client->dev.platform_data;
> pdata->exit_platform_hw();
>
So what happens if IRQ is raised here and work is scheduled again?
> free_irq(ts->irq, ts);
> - hrtimer_cancel(&ts->timer);
> input_unregister_device(ts->input);
> kfree(ts);
>
Could you please try the patch below and see if the touchscreen still
works for you? It should be applied on top of your patch.
Thanks!
--
Dmitry
Input: tsc2007 - properly shut off interrupts/delayed work
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
Properly shut off interrupts/delayed work by free-ing IRQ first
and then ensuring that enable/disable is balanced. Also add
__devinit/__devexit markings, restore poll delay/period scheduling
logic, make sure we call exit_platform_hw() method when probe
fails.
Signed-off-by: Dmitry Torokhov <dtor@...l.ru>
---
drivers/input/touchscreen/tsc2007.c | 76 ++++++++++++++++++++++-------------
1 files changed, 48 insertions(+), 28 deletions(-)
diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
index b512697..3c71e85 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -27,7 +27,8 @@
#include <linux/i2c.h>
#include <linux/i2c/tsc2007.h>
-#define TS_POLL_PERIOD msecs_to_jiffies(1) /* ms delay between samples */
+#define TS_POLL_DELAY 1 /* ms delay between samples */
+#define TS_POLL_PERIOD 1 /* ms delay between samples */
#define TSC2007_MEASURE_TEMP0 (0x0 << 4)
#define TSC2007_MEASURE_AUX (0x2 << 4)
@@ -76,7 +77,7 @@ struct tsc2007 {
u16 model;
u16 x_plate_ohms;
- unsigned pendown;
+ bool pendown;
int irq;
int (*get_pendown_state)(void);
@@ -131,18 +132,18 @@ static void tsc2007_send_event(void *tsc)
} else
rt = 0;
- /* Sample found inconsistent by debouncing or pressure is beyond
+ /*
+ * Sample found inconsistent by debouncing or pressure is beyond
* the maximum. Don't report it to user space, repeat at least
* once more the measurement
*/
if (rt > MAX_12BIT) {
dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
-
- schedule_delayed_work(&ts->work, TS_POLL_PERIOD);
return;
}
- /* NOTE: We can't rely on the pressure to determine the pen down
+ /*
+ * NOTE: We can't rely on the pressure to determine the pen down
* state, even this controller has a pressure sensor. The pressure
* value can fluctuate for quite a while after lifting the pen and
* in some cases may not even settle at the expected value.
@@ -157,7 +158,7 @@ static void tsc2007_send_event(void *tsc)
dev_dbg(&ts->client->dev, "DOWN\n");
input_report_key(input, BTN_TOUCH, 1);
- ts->pendown = 1;
+ ts->pendown = true;
}
input_report_abs(input, ABS_X, x);
@@ -169,8 +170,6 @@ static void tsc2007_send_event(void *tsc)
dev_dbg(&ts->client->dev, "point(%4d,%4d), pressure (%4u)\n",
x, y, rt);
}
-
- schedule_delayed_work(&ts->work, TS_POLL_PERIOD);
}
static int tsc2007_read_values(struct tsc2007 *tsc)
@@ -195,6 +194,7 @@ static void tsc2007_work(struct work_struct *work)
{
struct tsc2007 *ts =
container_of(to_delayed_work(work), struct tsc2007, work);
+
if (unlikely(!ts->get_pendown_state() && ts->pendown)) {
struct input_dev *input = ts->input;
@@ -204,7 +204,7 @@ static void tsc2007_work(struct work_struct *work)
input_report_abs(input, ABS_PRESSURE, 0);
input_sync(input);
- ts->pendown = 0;
+ ts->pendown = false;
enable_irq(ts->irq);
} else {
/* pen is still down, continue with the measurement */
@@ -212,6 +212,9 @@ static void tsc2007_work(struct work_struct *work)
tsc2007_read_values(ts);
tsc2007_send_event(ts);
+
+ schedule_delayed_work(&ts->work,
+ msecs_to_jiffies(TS_POLL_PERIOD));
}
}
@@ -221,7 +224,8 @@ static irqreturn_t tsc2007_irq(int irq, void *handle)
if (likely(ts->get_pendown_state())) {
disable_irq_nosync(ts->irq);
- schedule_delayed_work(&ts->work, 0);
+ schedule_delayed_work(&ts->work,
+ msecs_to_jiffies(TS_POLL_DELAY));
}
if (ts->clear_penirq)
@@ -230,8 +234,21 @@ static irqreturn_t tsc2007_irq(int irq, void *handle)
return IRQ_HANDLED;
}
-static int tsc2007_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
+static void tsc2007_free_irq(struct tsc2007 *ts)
+{
+ free_irq(ts->irq, ts);
+ if (cancel_delayed_work_sync(&ts->work)) {
+ /*
+ * Work was pending, therefore we need to enable
+ * IRQ here to balance the disable_irq() done in the
+ * interrupt handler.
+ */
+ enable_irq(ts->irq);
+ }
+}
+
+static int __devinit tsc2007_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
{
struct tsc2007 *ts;
struct tsc2007_platform_data *pdata = pdata = client->dev.platform_data;
@@ -255,17 +272,15 @@ static int tsc2007_probe(struct i2c_client *client,
}
ts->client = client;
- i2c_set_clientdata(client, ts);
-
+ ts->irq = client->irq;
ts->input = input_dev;
+ INIT_DELAYED_WORK(&ts->work, tsc2007_work);
ts->model = pdata->model;
ts->x_plate_ohms = pdata->x_plate_ohms;
ts->get_pendown_state = pdata->get_pendown_state;
ts->clear_penirq = pdata->clear_penirq;
- pdata->init_platform_hw();
-
snprintf(ts->phys, sizeof(ts->phys),
"%s/input0", dev_name(&client->dev));
@@ -280,12 +295,9 @@ static int tsc2007_probe(struct i2c_client *client,
input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);
+ pdata->init_platform_hw();
tsc2007_read_values(ts);
- ts->irq = client->irq;
-
- INIT_DELAYED_WORK(&ts->work, tsc2007_work);
-
err = request_irq(ts->irq, tsc2007_irq, 0,
client->dev.driver->name, ts);
if (err < 0) {
@@ -297,29 +309,37 @@ static int tsc2007_probe(struct i2c_client *client,
if (err)
goto err_free_irq;
+ i2c_set_clientdata(client, ts);
dev_info(&client->dev, "registered with irq (%d)\n", ts->irq);
return 0;
err_free_irq:
- free_irq(ts->irq, ts);
+ tsc2007_free_irq(ts);
+ pdata->exit_platform_hw();
err_free_mem:
input_free_device(input_dev);
kfree(ts);
return err;
}
-static int tsc2007_remove(struct i2c_client *client)
+static int __devexit tsc2007_remove(struct i2c_client *client)
{
struct tsc2007 *ts = i2c_get_clientdata(client);
- struct tsc2007_platform_data *pdata;
+ struct tsc2007_platform_data *pdata = client->dev.platform_data;
- cancel_delayed_work_sync(&ts->work);
+ free_irq(ts->irq, ts);
+ if (cancel_delayed_work_sync(&ts->work)) {
+ /*
+ * Work was pending, therefore we need to enable
+ * IRQ here to balance the disabel done in the
+ * interrupt handler.
+ */
+ enable_irq(ts->irq);
+ }
- pdata = client->dev.platform_data;
pdata->exit_platform_hw();
- free_irq(ts->irq, ts);
input_unregister_device(ts->input);
kfree(ts);
@@ -340,7 +360,7 @@ static struct i2c_driver tsc2007_driver = {
},
.id_table = tsc2007_idtable,
.probe = tsc2007_probe,
- .remove = tsc2007_remove,
+ .remove = __devexit_p(tsc2007_remove),
};
static int __init tsc2007_init(void)
--
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