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SubjectRe: [PATCH v6 2/6] input: touchscreen: ti_am335x_tsc: Remove udelay in interrupt handler


On Wednesday 07 January 2015 11:19 AM, Vignesh R wrote:
> From: Brad Griffis <bgriffis@ti.com>
>
> TSC interrupt handler had udelay to avoid reporting of false pen-up
> interrupt to user space. This patch implements workaround suggesting in
> Advisory 1.0.31 of silicon errata for am335x, thus eliminating udelay
> and touchscreen lag. This also improves performance of touchscreen and
> eliminates sudden jump of cursor at touch release.
>
> IDLECONFIG and CHARGECONFIG registers are to be configured
> with same values in order to eliminate false pen-up events. This
> workaround may result in false pen-down to be detected, hence considerable
> charge step delay needs to be added. The charge delay is set to 0xB000
> (in terms of ADC clock cycles) by default.
>
> TSC steps are disabled at the end of every sampling cycle and EOS bit is
> set. Once the EOS bit is set, the TSC steps need to be re-enabled to begin
> next sampling cycle.
>
> Signed-off-by: Brad Griffis <bgriffis@ti.com>
> [vigneshr@ti.com: Ported the patch from v3.12 to v3.19rc1]
>
> Signed-off-by: Vignesh R <vigneshr@ti.com>
> ---

Ping... Can somebody pick this patch series if there are no more comments??

> v5:
> - enable TSC steps only on EOS interrup
>
> v4:
> - check for PEN_IRQ bit in ADCFSM to avoid false-pen when ADC
> and TSC are used together.
> - Set charge delay to 0x400 as default. Most devices function
> normally at this value.
>
> drivers/input/touchscreen/ti_am335x_tsc.c | 67 ++++++++++++++-----------------
> include/linux/mfd/ti_am335x_tscadc.h | 3 +-
> 2 files changed, 33 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c b/drivers/input/touchscreen/ti_am335x_tsc.c
> index dfbb9fe6a270..0625c102a1d0 100644
> --- a/drivers/input/touchscreen/ti_am335x_tsc.c
> +++ b/drivers/input/touchscreen/ti_am335x_tsc.c
> @@ -173,11 +173,9 @@ static void titsc_step_config(struct titsc *ts_dev)
> titsc_writel(ts_dev, REG_STEPDELAY(i), STEPCONFIG_OPENDLY);
> }
>
> - /* Charge step configuration */
> - config = ts_dev->bit_xp | ts_dev->bit_yn |
> - STEPCHARGE_RFP_XPUL | STEPCHARGE_RFM_XNUR |
> - STEPCHARGE_INM_AN1 | STEPCHARGE_INP(ts_dev->inp_yp);
> + /* Make CHARGECONFIG same as IDLECONFIG */
>
> + config = titsc_readl(ts_dev, REG_IDLECONFIG);
> titsc_writel(ts_dev, REG_CHARGECONFIG, config);
> titsc_writel(ts_dev, REG_CHARGEDELAY, CHARGEDLY_OPENDLY);
>
> @@ -261,12 +259,34 @@ static irqreturn_t titsc_irq(int irq, void *dev)
> {
> struct titsc *ts_dev = dev;
> struct input_dev *input_dev = ts_dev->input;
> - unsigned int status, irqclr = 0;
> + unsigned int fsm, status, irqclr = 0;
> unsigned int x = 0, y = 0;
> unsigned int z1, z2, z;
> - unsigned int fsm;
>
> - status = titsc_readl(ts_dev, REG_IRQSTATUS);
> + status = titsc_readl(ts_dev, REG_RAWIRQSTATUS);
> + if (status & IRQENB_HW_PEN) {
> + ts_dev->pen_down = true;
> + titsc_writel(ts_dev, REG_IRQWAKEUP, 0x00);
> + titsc_writel(ts_dev, REG_IRQCLR, IRQENB_HW_PEN);
> + irqclr |= IRQENB_HW_PEN;
> + }
> +
> + 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);
> + } else {
> + ts_dev->pen_down = true;
> + }
> + irqclr |= IRQENB_PENUP;
> + }
> +
> + if (status & IRQENB_EOS)
> + irqclr |= IRQENB_EOS;
> +
> /*
> * ADC and touchscreen share the IRQ line.
> * FIFO1 interrupts are used by ADC. Handle FIFO0 IRQs here only
> @@ -297,37 +317,11 @@ static irqreturn_t titsc_irq(int irq, void *dev)
> }
> irqclr |= IRQENB_FIFO0THRES;
> }
> -
> - /*
> - * Time for sequencer to settle, to read
> - * correct state of the sequencer.
> - */
> - udelay(SEQ_SETTLE);
> -
> - status = titsc_readl(ts_dev, REG_RAWIRQSTATUS);
> - if (status & IRQENB_PENUP) {
> - /* Pen up event */
> - 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);
> - } else {
> - ts_dev->pen_down = true;
> - }
> - irqclr |= IRQENB_PENUP;
> - }
> -
> - if (status & IRQENB_HW_PEN) {
> -
> - titsc_writel(ts_dev, REG_IRQWAKEUP, 0x00);
> - titsc_writel(ts_dev, REG_IRQCLR, IRQENB_HW_PEN);
> - }
> -
> if (irqclr) {
> titsc_writel(ts_dev, REG_IRQSTATUS, irqclr);
> - am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);
> + if (status & IRQENB_EOS)
> + am335x_tsc_se_set_cache(ts_dev->mfd_tscadc,
> + ts_dev->step_mask);
> return IRQ_HANDLED;
> }
> return IRQ_NONE;
> @@ -417,6 +411,7 @@ static int titsc_probe(struct platform_device *pdev)
> }
>
> titsc_writel(ts_dev, REG_IRQENABLE, IRQENB_FIFO0THRES);
> + titsc_writel(ts_dev, REG_IRQENABLE, IRQENB_EOS);
> err = titsc_config_wires(ts_dev);
> if (err) {
> dev_err(&pdev->dev, "wrong i/p wire configuration\n");
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> index e2e70053470e..3f4e994ace2b 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -52,6 +52,7 @@
>
> /* IRQ enable */
> #define IRQENB_HW_PEN BIT(0)
> +#define IRQENB_EOS BIT(1)
> #define IRQENB_FIFO0THRES BIT(2)
> #define IRQENB_FIFO0OVRRUN BIT(3)
> #define IRQENB_FIFO0UNDRFLW BIT(4)
> @@ -107,7 +108,7 @@
> /* Charge delay */
> #define CHARGEDLY_OPEN_MASK (0x3FFFF << 0)
> #define CHARGEDLY_OPEN(val) ((val) << 0)
> -#define CHARGEDLY_OPENDLY CHARGEDLY_OPEN(1)
> +#define CHARGEDLY_OPENDLY CHARGEDLY_OPEN(0x400)
>
> /* Control register */
> #define CNTRLREG_TSCSSENB BIT(0)
>


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