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Date: Tue, 14 Jul 2009 10:47:53 +0200
From: Richard Röjfors
<richard.rojfors.ext@...ean-labs.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.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
On 7/14/09 6:59 AM, Dmitry Torokhov wrote:
> 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?
Good point, scheduling of the work queue takes some time, but of course
that varies.
>
>> }
>>
>> 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?
We should.
>
>> 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.
I have modified my code accordingly to most of your changes. I don't
have any platform callbacks in my platform, so make sure those are
optional. Will try it out!
--Richard
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