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authorImre Deak <imre.deak@nokia.com>2006-04-11 23:41:49 -0400
committerDmitry Torokhov <dtor_core@ameritech.net>2006-04-11 23:41:49 -0400
commit53a0ef89e95c725f3faab98573770aeb7429c1a3 (patch)
tree66d9258d53621f86ac686f768d17885404edced6 /drivers/input
parent438f2a7401ec5d8f85923a7c3e6da444f097a3a1 (diff)
Input: ads7846 - power down ADC a bit later
Submit a seperate request for powering down the ADC in ads7846, doing it after the last read request. Otherwise some of the read values are incorrect. Signed-off-by: Imre Deak <imre.deak@nokia.com> Signed-off-by: Juha Yrjola <juha.yrjola@nokia.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Diffstat (limited to 'drivers/input')
-rw-r--r--drivers/input/touchscreen/ads7846.c21
1 files changed, 18 insertions, 3 deletions
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 7f384a694d8..54d43347786 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -72,10 +72,11 @@ struct ads7846 {
u16 vref_delay_usecs;
u16 x_plate_ohms;
- u8 read_x, read_y, read_z1, read_z2;
+ u8 read_x, read_y, read_z1, read_z2, pwrdown;
+ u16 dummy; /* for the pwrdown read */
struct ts_event tc;
- struct spi_transfer xfer[8];
+ struct spi_transfer xfer[10];
struct spi_message msg;
spinlock_t lock;
@@ -125,7 +126,9 @@ struct ads7846 {
#define READ_Y (READ_12BIT_DFR(y) | ADS_PD10_ADC_ON)
#define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
#define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)
-#define READ_X (READ_12BIT_DFR(x) | ADS_PD10_PDOWN) /* LAST */
+
+#define READ_X (READ_12BIT_DFR(x) | ADS_PD10_ADC_ON)
+#define PWRDOWN (READ_12BIT_DFR(y) | ADS_PD10_PDOWN) /* LAST */
/* single-ended samples need to first power up reference voltage;
* we leave both ADC and VREF powered
@@ -541,6 +544,18 @@ static int __devinit ads7846_probe(struct spi_device *spi)
x++;
x->rx_buf = &ts->tc.x;
x->len = 2;
+ spi_message_add_tail(x, &ts->msg);
+
+ /* power down */
+ x++;
+ ts->pwrdown = PWRDOWN;
+ x->tx_buf = &ts->pwrdown;
+ x->len = 1;
+ spi_message_add_tail(x, &ts->msg);
+
+ x++;
+ x->rx_buf = &ts->dummy;
+ x->len = 2;
CS_CHANGE(*x);
spi_message_add_tail(x, &ts->msg);