AM3354: TSC2046 driver issue

Hi all,

I am using custom board with AM3354 SoC. Board is copy of BeagleBone Black + TSC2046 connected to SPI0 CS0 which is used for touchscreen controller of the AM-1024768FTMQW-T00H LCD.

I use Processor SDK Linux  06_01_00_08.

In order to get any response when I touch the display I had to modify the ads7846.c driver as shown bellow:

 /*
 * We'd set TX word size 8 bits and RX word size to 13 bits ... except
 * that even if the hardware can do that, the SPI controller driver
 * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 */

-   spi->bits_per_word = 8;   
+  spi->bits_per_word = 16;

-   spi->mode = SPI_MODE_0;
+  spi->mode = SPI_MODE_1;
    err = spi_setup(spi);
    if (err < 0)

However, when I touch the display I start getting the following error outputted continuously:
[ 1487.869143] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1487.889109] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1487.909106] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1487.929139] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1487.949088] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1487.969110] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1487.989070] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1488.009115] ads7846 spi0.0: spi_sync --> -22                                                        
[ 1488.029154] ads7846 spi0.0: spi_sync --> -22

Here is my dts node:
&spi0 {
        pinctrl-names = "default";
        pinctrl-0 = <&spi0_pins>;
        status = "okay";
    tsc2046@0 {
        reg = <0>;    
        compatible = "ti,tsc2046";
        interrupt-parent = <&gpio3>;
        interrupts = <14 0>;    
        spi-max-frequency = <1000000>;
        pendown-gpio = <&gpio3 14 0>;

        ti,x-min = /bits/ 16 <0>;
        ti,x-max = /bits/ 16 <8000>;
        ti,y-min = /bits/ 16 <0>;
        ti,y-max = /bits/ 16 <4800>;
        ti,x-plate-ohms = /bits/ 16 <350>;
        ti,pressure-max = /bits/ 16 <255>;
        wakeup-source;
    };

};

I seem to get the touchscreen controller registered & initialized in the kernel:

[    4.327498] ads7846 spi0.0: spi0.0 supply vcc not found, using dummy regulator                       
[    4.334991] ads7846 spi0.0: Linked as a consumer to regulator.0                                      
[    4.341408] ads7846 spi0.0: touchscreen, irq 55
[    4.346128] input: ADS7846 Touchscreen as /devices/platform/ocp/48030000.spi/spi_master/spi0/spi0.0/0

I am able to see the gpio3_14 registered in /proc/interrupts as irq for ads7846:
52:          0      INTC 111 Level     48310000.rng                                                    
 53:        965      INTC  37 Level     SGX ISR                                                         
 55:          0  481ae000.gpio  14 Edge      ads7846                                                    
 56:          0  44e07000.gpio   6 Edge      48060000.mmc cd                                           
I see the irq incrementing when tapping on the display, but at the same time the kernel starts continously outputting ads7846 spi0.0: spi_sync --> -22, the part where this error comes from is: 
ads7846_read_state() ->
   while (msg_idx < ts->msg_count) {

        ts->wait_for_sync();

        m = &ts->msg[msg_idx];

        error = spi_async(ts->spi, m);//error = spi_sync(ts->spi, m);

        if (error) {
            dev_err(&ts->spi->dev, "spi_async --> %d\n", error);
            packet->tc.ignore = true;
            return;
        }

which can be tracked to spi.c driver, where spi_sync() is implemented. The error -22 seems to indicate that the message is of incompatible type (include/uapi/asm-generic/errno-base.h):
#define    EINVAL        22    /* Invalid argument */

Also when ads7846 spi0.0: spi_sync --> -22, there is NO signal on the spi bus. The ads7846.c cannot read the touchscreen data from the TSC2046. 

Previously I've used a customized driver with kernel 3.2 (Sitara Linux SDK 06.00.00.00) and it worked, but now the requirement is to stick with PROCESSOR SDK LINUX (kernel mainline) sources, so I have to use ads7846.c.

Can anyone help with pointers on what might be wrong?

Thanks and regards.