Input: atmel_tsadcc - improve accuracy

Discard the last sample just before pen is up because it is quite often
errorneous.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Dan Liang <dan.liang@atmel.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 24 insertions, 13 deletions

diff --git a/drivers/input/touchscreen/atmel_tsadcc.c b/drivers/input/touchscreen/atmel_tsadcc.c
index eee126b19e8b..a89a6a8f05e6 100644
--- a/drivers/input/touchscreen/atmel_tsadcc.c
+++ b/drivers/input/touchscreen/atmel_tsadcc.c
@@ -91,6 +91,9 @@ struct atmel_tsadcc {
         char                    phys[32];
         struct clk              *clk;
         int                     irq;
+        unsigned int            prev_absx;
+        unsigned int            prev_absy;
+        unsigned char           bufferedmeasure;
 };
 
 static void __iomem             *tsc_base;
@@ -100,10 +103,9 @@ static void __iomem		*tsc_base;
 
 static irqreturn_t atmel_tsadcc_interrupt(int irq, void *dev)
 {
-        struct input_dev *input_dev = ((struct atmel_tsadcc *)dev)->input;
+        struct atmel_tsadcc     *ts_dev = (struct atmel_tsadcc *)dev;
+        struct input_dev        *input_dev = ts_dev->input;
 
-        unsigned int absx;
-        unsigned int absy;
         unsigned int status;
         unsigned int reg;
 
@@ -121,6 +123,7 @@ static irqreturn_t atmel_tsadcc_interrupt(int irq, void *dev)
                 atmel_tsadcc_write(ATMEL_TSADCC_IER, ATMEL_TSADCC_PENCNT);
 
                 input_report_key(input_dev, BTN_TOUCH, 0);
+                ts_dev->bufferedmeasure = 0;
                 input_sync(input_dev);
 
         } else if (status & ATMEL_TSADCC_PENCNT) {
@@ -138,16 +141,23 @@ static irqreturn_t atmel_tsadcc_interrupt(int irq, void *dev)
         } else if (status & ATMEL_TSADCC_EOC(3)) {
                 /* Conversion finished */
 
-                absx = atmel_tsadcc_read(ATMEL_TSADCC_CDR3) << 10;
-                absx /= atmel_tsadcc_read(ATMEL_TSADCC_CDR2);
-
-                absy = atmel_tsadcc_read(ATMEL_TSADCC_CDR1) << 10;
-                absy /= atmel_tsadcc_read(ATMEL_TSADCC_CDR0);
-
-                input_report_abs(input_dev, ABS_X, absx);
-                input_report_abs(input_dev, ABS_Y, absy);
-                input_report_key(input_dev, BTN_TOUCH, 1);
-                input_sync(input_dev);
+                if (ts_dev->bufferedmeasure) {
+                        /* Last measurement is always discarded, since it can
+                         * be erroneous.
+                         * Always report previous measurement */
+                        input_report_abs(input_dev, ABS_X, ts_dev->prev_absx);
+                        input_report_abs(input_dev, ABS_Y, ts_dev->prev_absy);
+                        input_report_key(input_dev, BTN_TOUCH, 1);
+                        input_sync(input_dev);
+                } else
+                        ts_dev->bufferedmeasure = 1;
+
+                /* Now make new measurement */
+                ts_dev->prev_absx = atmel_tsadcc_read(ATMEL_TSADCC_CDR3) << 10;
+                ts_dev->prev_absx /= atmel_tsadcc_read(ATMEL_TSADCC_CDR2);
+
+                ts_dev->prev_absy = atmel_tsadcc_read(ATMEL_TSADCC_CDR1) << 10;
+                ts_dev->prev_absy /= atmel_tsadcc_read(ATMEL_TSADCC_CDR0);
         }
 
         return IRQ_HANDLED;
@@ -223,6 +233,7 @@ static int __devinit atmel_tsadcc_probe(struct platform_device *pdev)
         }
 
         ts_dev->input = input_dev;
+        ts_dev->bufferedmeasure = 0;
 
         snprintf(ts_dev->phys, sizeof(ts_dev->phys),
                  "%s/input0", pdev->dev.bus_id);