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Message-ID: <20141110091123.GC21424@x1>
Date: Mon, 10 Nov 2014 09:11:23 +0000
From: Lee Jones <lee.jones@...aro.org>
To: Vignesh R <vigneshr@...com>
Cc: Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
Benoit Cousson <bcousson@...libre.com>,
Tony Lindgren <tony@...mide.com>,
Russell King <linux@....linux.org.uk>,
Jonathan Cameron <jic23@...nel.org>,
Hartmut Knaack <knaack.h@....de>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Lars-Peter Clausen <lars@...afoo.de>,
Peter Meerwald <pmeerw@...erw.net>,
Samuel Ortiz <sameo@...ux.intel.com>,
Felipe Balbi <balbi@...com>, Brad Griffis <bgriffis@...com>,
Sanjeev Sharma <sanjeev_sharma@...tor.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Jan Kardell <jan.kardell@...liq.com>,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-iio@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH 2/5] input: touchscreen: ti_am335x_tsc: Remove udelay in
interrupt handler
On Fri, 07 Nov 2014, Vignesh R wrote:
> From: Brad Griffis <bgriffis@...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@...com>
> [vigneshr@...com: Ported the patch from v3.12 to v3.18rc2]
>
> Signed-off-by: Vignesh R <vigneshr@...com>
> ---
> drivers/input/touchscreen/ti_am335x_tsc.c | 56 ++++++++++++-------------------
> include/linux/mfd/ti_am335x_tscadc.h | 3 +-
Acked-by: Lee Jones <lee.jones@...aro.org>
> 2 files changed, 24 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c b/drivers/input/touchscreen/ti_am335x_tsc.c
> index 1aeac9675fe7..483fd97c0e0c 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);
>
> @@ -264,9 +262,26 @@ static irqreturn_t titsc_irq(int irq, void *dev)
> unsigned int 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) {
> + 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);
> + 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
> @@ -297,34 +312,6 @@ 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);
> @@ -417,6 +404,7 @@ 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..c99be5dc0f5c 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(0xB000)
>
> /* Control register */
> #define CNTRLREG_TSCSSENB BIT(0)
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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