Linux/AM3358: TSC PEN_UP interrupt issue

Reference EVM design 。
I find the reason.
ti_am335x_tsc.c file
the titsc_probe function,when it init the IRQ, the PEN_UP and PEN_DOWN interrupt are not enabled,why do this?

ps：

in my test,the irq function get the interrupt,but sometimes it can not report the PENUP event .I find when get the PENUP event,the fsm value is 0x50 not 0x10,why this happen?

if (status & IRQENB_PENUP) {
fsm = titsc_readl(ts_dev, REG_ADCFSM);
printk("[huzz]%s:fsm=0x%x\n",__func__,fsm);
if (fsm == ADCFSM_STEPID) {
ts_dev->pen_down = false;
input_report_key(input_dev, BTN_TOUCH, 0);
input_report_abs(input_dev, ABS_PRESSURE, 0);
input_sync(input_dev);
pm_relax(ts_dev->mfd_tscadc->dev);
} else {
ts_dev->pen_down = true;
}
irqclr |= IRQENB_PENUP;
}

Hi,

the titsc_probe function,when it init the IRQ, the PEN_UP and PEN_DOWN interrupt are not enabled,why do this?

The driver actually uses the IRQSTATUS_RAW register to determine if there is a pen_up or pen_down event, see titsc_irq():
status = titsc_readl(ts_dev, REG_RAWIRQSTATUS);
........
if (status & IRQENB_PENUP) {
fsm = titsc_readl(ts_dev, REG_ADCFSM);
if (fsm == ADCFSM_STEPID) {
ts_dev->pen_down = false;
input_report_key(input_dev, BTN_TOUCH, 0);
input_report_abs(input_dev, ABS_PRESSURE, 0);
input_sync(input_dev);
pm_relax(ts_dev->mfd_tscadc->dev);
} else {
ts_dev->pen_down = true;
}
irqclr |= IRQENB_PENUP;
}

So there is no need to set the irq in IRQENABLE_SET register in titsc_probe().

As for the problem you have:
1. I understand this is a custom board, so try lowering the x-plate-resistance to lower the pressure needed for pendown & penup interrupts.
2. As far as I know the latest sdk does NOT use tslib.. It uses the weston libraries... Try rebuilding your qt app with wayland-egl support.

Best Regards,
Yordan

Hi,

Bellow information is strictly general info from my experience with TI TSC controllers. 

z1 & z2 are two additional cross panel measurements (The END result Z = (Z+2047) >>12; is the actual pressure):

"To determine pen or finger touch, the pressure of the touch must be determined. Generally, it is not necessary to have very high performance for this test; therefore, 10-bit resolution mode is recommended (however, data sheet calculations are shown using 12-bit resolution mode). There are several different ways of performing this measurement. The TSC2005 supports two methods. The first method requires knowing the X-plate resistance, the measurement of the X-Position, and two additional cross panel measurements (Z2 and Z1) of the touch screen"

The reference block diagram of the above is usually as follows:

  

There are two equations, that can be used to calculate the pressure. One is the most commonly used (implemented in ti_am335x_tsc.c):
    

The SECOND is as follows: 
   

Again from my experience with some resistive displays, when the touch screen behaved strange (random behavior when touching the screen, when there were some spikes & offsets with the touch point), the SECOND equation sowed better performance. Again this was a strictly trial and error finding, and in my opinion is use case dependent. 

Now as far as your pen up interrupt not being processed. See Section 12.3.5 Interrupts of AM335x TRM: 
 "A Pen-up event interrupt, also known as the Pen-up interrupt, can only be generated when using HW steps with the charge steps enabled. If a Pen-down event caused the HW steps to be scheduled and no Pen-down is present after the sequencer finished servicing the charge step, then a Pen-up interrupt is generated. To detect Pen-up interrupts, the charge step must share the same configuration as the idle step." 

Check the code within if (status & IRQENB_PENUP) of the ti_am335x_tsc.c driver. Print the values of status & IRQENB_PENUP, to see if these have been updated. Make sure the sequence described in Section 12.3.5 is implemented correctly. 

Best Regards, 
Yordan