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Input: ads7846 - introduce platform specific way to synchronize sampling

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Noises can be introduced when LCD signals are being driven, some platforms
provide a signal to assist the synchronization of this sampling procedure.

Signed-off-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Eric Miao
2009-04-11 16:54:59 -07:00
committed by Dmitry Torokhov
parent b79e83bdd9
commit fd746d540a
2 changed files with 11 additions and 0 deletions
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10
drivers/input/touchscreen/ads7846.c
View File

@@ -127,6 +127,8 @@ struct ads7846 {
void (*filter_cleanup)(void *data); void (*filter_cleanup)(void *data);
int (*get_pendown_state)(void); int (*get_pendown_state)(void);
int gpio_pendown; int gpio_pendown;
void (*wait_for_sync)(void);
}; };
/* leave chip selected when we're done, for quicker re-select? */ /* leave chip selected when we're done, for quicker re-select? */
@@ -511,6 +513,10 @@ static int get_pendown_state(struct ads7846 *ts)
return !gpio_get_value(ts->gpio_pendown); return !gpio_get_value(ts->gpio_pendown);
} }
static void null_wait_for_sync(void)
{
}
/* /*
* PENIRQ only kicks the timer. The timer only reissues the SPI transfer, * PENIRQ only kicks the timer. The timer only reissues the SPI transfer,
* to retrieve touchscreen status. * to retrieve touchscreen status.
@@ -686,6 +692,7 @@ static void ads7846_rx_val(void *ads)
default: default:
BUG(); BUG();
} }
ts->wait_for_sync();
status = spi_async(ts->spi, m); status = spi_async(ts->spi, m);
if (status) if (status)
dev_err(&ts->spi->dev, "spi_async --> %d\n", dev_err(&ts->spi->dev, "spi_async --> %d\n",
@@ -723,6 +730,7 @@ static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
} else { } else {
/* pen is still down, continue with the measurement */ /* pen is still down, continue with the measurement */
ts->msg_idx = 0; ts->msg_idx = 0;
ts->wait_for_sync();
status = spi_async(ts->spi, &ts->msg[0]); status = spi_async(ts->spi, &ts->msg[0]);
if (status) if (status)
dev_err(&ts->spi->dev, "spi_async --> %d\n", status); dev_err(&ts->spi->dev, "spi_async --> %d\n", status);
@@ -947,6 +955,8 @@ static int __devinit ads7846_probe(struct spi_device *spi)
ts->penirq_recheck_delay_usecs = ts->penirq_recheck_delay_usecs =
pdata->penirq_recheck_delay_usecs; pdata->penirq_recheck_delay_usecs;
ts->wait_for_sync = pdata->wait_for_sync ? : null_wait_for_sync;
snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev)); snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&spi->dev));
input_dev->name = "ADS784x Touchscreen"; input_dev->name = "ADS784x Touchscreen";

1
include/linux/spi/ads7846.h
View File

@@ -51,5 +51,6 @@ struct ads7846_platform_data {
void **filter_data); void **filter_data);
int (*filter) (void *filter_data, int data_idx, int *val); int (*filter) (void *filter_data, int data_idx, int *val);
void (*filter_cleanup)(void *filter_data); void (*filter_cleanup)(void *filter_data);
void (*wait_for_sync)(void);
}; };