Hello Benson,

Is the problem that the 224e is missing T28 object?
This change seems extremely 224/224e specific. This driver, however,
supports Atmel touch devices that are neither 224 or 224e, many have
the  SPT_CTECONFIG_T28 object.

yes, I only have access to 224 and 224e; it is not clear what devices are 
supposed to be supported

The driver does read out a supported object table from the device
during initialize before handle_pdata. What sort of problem is there
in trying to write the voltage to a non existent T28 object?  If the
object is missing, then mxt_write_object for voltage should simply
return -EINVAL, and no harm should be done.

a bogus error message is written, 'Invalid object type' in 
mxt_get_object()

On Thu, Feb 7, 2013 at 6:17 AM, Peter Meerwald [off-list ref] wrote:

quoted

From: Peter Meerwald <redacted>

only the mxt224 has a SPT_CTECONFIG_T28 object, the mxt224e doesn't

Signed-off-by: Peter Meerwald <redacted>
---
 drivers/input/touchscreen/atmel_mxt_ts.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 63a82bb..17cc15a 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c

@@ -41,6 +41,10 @@
 #define MXT_OBJECT_NUM         0x06
 #define MXT_OBJECT_START       0x07

+/* Family IDs */
+#define MXT224_ID      0x80
+#define MXT224E_ID     0x81
+
 #define MXT_OBJECT_SIZE                6

 /* Object types */

@@ -687,7 +691,7 @@ static void mxt_handle_pdata(struct mxt_data *data)
                        MXT_TOUCH_YRANGE_MSB, (pdata->y_size - 1) >> 8);

        /* Set touchscreen voltage */
-       if (pdata->voltage) {
+       if (pdata->voltage && data->info.family_id == MXT224_ID) {

As an alternative, could you not check for the existence of the
voltage object in the table here using mxt_get_object rather than
specifically switching on family ID number?

yes, I think that is a good suggestion

quoted

                if (pdata->voltage < MXT_VOLTAGE_DEFAULT) {
                        voltage = (MXT_VOLTAGE_DEFAULT - pdata->voltage) /
                                MXT_VOLTAGE_STEP;

regards, p. 

-- 

Peter Meerwald
+43-664-2444418 (mobile)