From 53a0ef89e95c725f3faab98573770aeb7429c1a3 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Tue, 11 Apr 2006 23:41:49 -0400 Subject: 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 Signed-off-by: Juha Yrjola Signed-off-by: David Brownell Signed-off-by: Dmitry Torokhov --- drivers/input/touchscreen/ads7846.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'drivers/input/touchscreen/ads7846.c') diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index 7f384a694d80..54d433477860 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); -- cgit v1.2.3