Noices can be introduced when LCD signals are being driven, some platforms
provide a signal to assist the synchronization of this sampling procedure,
introduce a platform specific 'wait_for_sync' for this.
Signed-off-by: Eric Miao <eric.miao@xxxxxxxxxxx>
Cc: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/input/touchscreen/ads7846.c | 10 ++++++++++
include/linux/spi/ads7846.h | 2 ++
2 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 7c27c8b..e18775a 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -127,6 +127,8 @@ struct ads7846 {
void (*filter_cleanup)(void *data);
int (*get_pendown_state)(void);
int gpio_pendown;
+
+ void (*wait_for_sync)(void);
};
/* 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);
}
+static void null_wait_for_sync(void)
+{
+}
+
/*
* PENIRQ only kicks the timer. The timer only reissues the SPI transfer,
* to retrieve touchscreen status.
@@ -686,6 +692,7 @@ static void ads7846_rx_val(void *ads)
default:
BUG();
}
+ ts->wait_for_sync();
status = spi_async(ts->spi, m);
if (status)
dev_err(&ts->spi->dev, "spi_async --> %d\n",
@@ -723,6 +730,7 @@ static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
} else {
/* pen is still down, continue with the measurement */
ts->msg_idx = 0;
+ ts->wait_for_sync();
status = spi_async(ts->spi, &ts->msg[0]);
if (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 =
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));
input_dev->name = "ADS784x Touchscreen";
diff --git a/include/linux/spi/ads7846.h b/include/linux/spi/ads7846.h
index 05eab2f..186c5aa 100644
--- a/include/linux/spi/ads7846.h
+++ b/include/linux/spi/ads7846.h
@@ -51,5 +51,7 @@ struct ads7846_platform_data {
void **filter_data);
int (*filter) (void *filter_data, int data_idx, int *val);
void (*filter_cleanup)(void *filter_data);
+
+ void (*wait_for_sync)(void);
};
--
1.6.0.4
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