Hi added the printk. this is my code

static void ads7846_report_state(struct ads7846 *ts)
{
    struct ads7846_packet *packet = ts->packet;
    unsigned int Rt;
    u16 x, y, z1, z2;

    /* added for debug */
    printk(KERN_INFO "ads7846_report_state\n");

    /*
    * ads7846_get_value() does in-place conversion (including byte swap)
    * from on-the-wire format as part of debouncing to get stable
    * readings.
    */
    if (ts->model == 7845) {
        x = *(u16 *)packet->tc.x_buf;
        y = *(u16 *)packet->tc.y_buf;
        z1 = 0;
        z2 = 0;
    } else {
        x = packet->tc.x;
        y = packet->tc.y;
        z1 = packet->tc.z1;
        z2 = packet->tc.z2;
    }

    /* range filtering */
    if (x == MAX_12BIT)
        x = 0;

    if (ts->model == 7843) {
        Rt = ts->pressure_max / 2;
    } else if (ts->model == 7845) {
        if (get_pendown_state(ts)) {
            Rt = ts->pressure_max / 2;
        } else {
            /* added for debug */
            printk(KERN_INFO "cannot get pendown state \n");
            Rt = 0;
        }
        dev_vdbg(&ts->spi->dev, "x/y: %d/%d, PD %d\n", x, y, Rt);
    } else if (likely(x && z1)) {
        /* compute touch pressure resistance using equation #2 */
        /* added for debug */
        printk(KERN_INFO "compute touch pressure resistance using equation #2 \n");
        Rt = z2;
        Rt -= z1;
        Rt *= x;
        Rt *= ts->x_plate_ohms;
        Rt /= z1;
        Rt = (Rt + 2047) >> 12;
    } else {
        /* added for debug */
        printk(KERN_INFO "ts model ? %d \n", ts->model);
        Rt = 0;
    }
    /* added for debug */
    printk(KERN_INFO "Rt %d \n", Rt);

    /*
    * Sample found inconsistent by debouncing or pressure is beyond
    * the maximum. Don't report it to user space, repeat at least
    * once more the measurement
    */
    if (packet->tc.ignore || Rt > ts->pressure_max) {
        /* added for debug */
        printk(KERN_INFO "Ignored %d pressure %d \n", packet->tc.ignore, Rt);

        dev_vdbg(&ts->spi->dev, "ignored %d pressure %d \n",
            packet->tc.ignore, Rt);
        return;
    }

    /*
    * Maybe check the pendown state before reporting. This discards
    * false readings when the pen is lifted.
    */
    if (ts->penirq_recheck_delay_usecs) {
        udelay(ts->penirq_recheck_delay_usecs);
        if (!get_pendown_state(ts)) {
            /* added for debug */
            printk(KERN_INFO "cannot get pendown state \n");
            Rt = 0;
        }
    }

    /*
    * NOTE: We can't rely on the pressure to determine the pen down
    * state, even this controller has a pressure sensor. The pressure
    * value can fluctuate for quite a while after lifting the pen and
    * in some cases may not even settle at the expected value.
    *
    * The only safe way to check for the pen up condition is in the
    * timer by reading the pen signal state (it's a GPIO _and_ IRQ).
    */
    if (Rt) {
        struct input_dev *input = ts->input;

        if (ts->swap_xy)
            swap(x, y);

        if (!ts->pendown) {
            input_report_key(input, BTN_TOUCH, 1);
            ts->pendown = true;
            dev_vdbg(&ts->spi->dev, "DOWN\n");
        }

        /* added for debug */
        printk(KERN_INFO "input_report_abs x: %d, y: %d \n", x, y);

        input_report_abs(input, ABS_X, x);
        input_report_abs(input, ABS_Y, y);
        input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);

        input_sync(input);
        dev_vdbg(&ts->spi->dev, "%4d/%4d/%4d\n", x, y, Rt);
    } else {
        /* added for debug */
        printk(KERN_INFO "not reporting. Rt=%d \n", Rt);
    }
}

and the output after touching the screen

<6>[   59.531036] ads7846_report_state
<6>[   59.534423] compute touch pressure resistance using equation #2
<6>[   59.540771] Rt 0
<6>[   59.542785] not reporting. Rt=0
<6>[   59.553497] ads7846_report_state
<6>[   59.556884] compute touch pressure resistance using equation #2
<6>[   59.563201] Rt 0
<6>[   59.565216] not reporting. Rt=0
<6>[   59.577087] ads7846_report_state
<6>[   59.580474] compute touch pressure resistance using equation #2
<6>[   59.586791] Rt 0
<6>[   59.588836] not reporting. Rt=0
<6>[   59.850494] ads7846_report_state
<6>[   59.853881] compute touch pressure resistance using equation #2
<6>[   59.860198] Rt 0
<6>[   59.862213] not reporting. Rt=0

Thanks
Francesco

2012/2/15 Francesco Sarasini <sarasini@gmail.com>

Thank you. My code base is Linaro Android.
I will add the printk to the code

Francesco

2012/2/15 Bharathi Subramanian <bharathi.list@gmail.com>

On Tue, Feb 14, 2012 at 7:48 PM, Francesco Sarasini <sarasini@gmail.com> wrote:

>>> Please add printk to show the value of x, y, before and after the
>>> OMAP3EVM macro. That will give better idea about the touchevent.

>> I'm sorry, where is the OMAP3EVM macro?

Oops. I hope, it is in EVM Code. For BB-xM, it might be different.

The following set of commands are responsible for sending the
co-ordinates to user space. You have to add printk before this and
check.

input_report_abs(input, ABS_X, x);
input_report_abs(input, ABS_Y, y);
input_report_abs(input, ABS_PRESSURE, ts->pressure_max - Rt);

Can you share info about code base (Rowboat/Linaro) ?

Bye :)
--
Bharathi Subramanian