---

yaml
---
r: 62168
b: refs/heads/master
c: e4f4886
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 4994cd8dadcf9d484ab3ec19f3c7c7a4e5353c1c
+refs/heads/master: e4f48861993294c27849076741eb0c090482560b

trunk/drivers/input/touchscreen/ads7846.c

@@ -95,7 +95,7 @@ struct ads7846 {
 	u16			dummy;		/* for the pwrdown read */
 	struct ts_event		tc;
 
-	struct spi_transfer	xfer[10];
+	struct spi_transfer	xfer[18];
 	struct spi_message	msg[5];
 	struct spi_message	*last_msg;
 	int			msg_idx;
@@ -936,6 +936,24 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 	x->len = 2;
 	spi_message_add_tail(x, m);
 
+	/* the first sample after switching drivers can be low quality;
+	 * optionally discard it, using a second one after the signals
+	 * have had enough time to stabilize.
+	 */
+	if (pdata->settle_delay_usecs) {
+		x->delay_usecs = pdata->settle_delay_usecs;
+
+		x++;
+		x->tx_buf = &ts->read_y;
+		x->len = 1;
+		spi_message_add_tail(x, m);
+
+		x++;
+		x->rx_buf = &ts->tc.y;
+		x->len = 2;
+		spi_message_add_tail(x, m);
+	}
+
 	m->complete = ads7846_rx_val;
 	m->context = ts;
 
@@ -954,6 +972,21 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 	x->len = 2;
 	spi_message_add_tail(x, m);
 
+	/* ... maybe discard first sample ... */
+	if (pdata->settle_delay_usecs) {
+		x->delay_usecs = pdata->settle_delay_usecs;
+
+		x++;
+		x->tx_buf = &ts->read_x;
+		x->len = 1;
+		spi_message_add_tail(x, m);
+
+		x++;
+		x->rx_buf = &ts->tc.x;
+		x->len = 2;
+		spi_message_add_tail(x, m);
+	}
+
 	m->complete = ads7846_rx_val;
 	m->context = ts;
 
@@ -973,6 +1006,21 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 		x->len = 2;
 		spi_message_add_tail(x, m);
 
+		/* ... maybe discard first sample ... */
+		if (pdata->settle_delay_usecs) {
+			x->delay_usecs = pdata->settle_delay_usecs;
+
+			x++;
+			x->tx_buf = &ts->read_z1;
+			x->len = 1;
+			spi_message_add_tail(x, m);
+
+			x++;
+			x->rx_buf = &ts->tc.z1;
+			x->len = 2;
+			spi_message_add_tail(x, m);
+		}
+
 		m->complete = ads7846_rx_val;
 		m->context = ts;
 
@@ -990,6 +1038,21 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 		x->len = 2;
 		spi_message_add_tail(x, m);
 
+		/* ... maybe discard first sample ... */
+		if (pdata->settle_delay_usecs) {
+			x->delay_usecs = pdata->settle_delay_usecs;
+
+			x++;
+			x->tx_buf = &ts->read_z2;
+			x->len = 1;
+			spi_message_add_tail(x, m);
+
+			x++;
+			x->rx_buf = &ts->tc.z2;
+			x->len = 2;
+			spi_message_add_tail(x, m);
+		}
+
 		m->complete = ads7846_rx_val;
 		m->context = ts;
 	}

trunk/include/linux/spi/ads7846.h

@@ -16,6 +16,14 @@ struct ads7846_platform_data {
 	u16	vref_delay_usecs;	/* 0 for external vref; etc */
 	int	keep_vref_on:1;		/* set to keep vref on for differential
 					 * measurements as well */
+
+	/* Settling time of the analog signals; a function of Vcc and the
+	 * capacitance on the X/Y drivers.  If set to non-zero, two samples
+	 * are taken with settle_delay us apart, and the second one is used.
+	 * ~150 uSec with 0.01uF caps.
+	 */
+	u16	settle_delay_usecs;
+
 	u16	x_plate_ohms;
 	u16	y_plate_ohms;