On Mon, 27 Oct 2014, Vignesh R wrote:
> From: Brad Griffis <bgriffis@xxxxxx>
>
> 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.
>
> In one shot mode, sequencer automatically disables all enabled steps at
> the end of each cycle. (both ADC steps and TSC steps) Hence these steps
> need not be saved in reg_se_cache for clearing these steps at a later
> stage.
>
> Signed-off-by: Brad Griffis <bgriffis@xxxxxx>
> [vigneshr@xxxxxx: Ported patch from v3.12 to v3.18rc2]
> Signed-off-by: Vignesh R <vigneshr@xxxxxx>
> ---
> drivers/input/touchscreen/ti_am335x_tsc.c | 56 ++++++++++++-------------------
> drivers/mfd/ti_am335x_tscadc.c | 7 ++--
> include/linux/mfd/ti_am335x_tscadc.h | 4 ++-
> 3 files changed, 30 insertions(+), 37 deletions(-)
[...]
> diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
> index d877e777cce6..94ef8992f46b 100644
> --- a/drivers/mfd/ti_am335x_tscadc.c
> +++ b/drivers/mfd/ti_am335x_tscadc.c
> @@ -86,8 +86,12 @@ static void am335x_tscadc_need_adc(struct ti_tscadc_dev *tsadc)
> spin_lock_irq(&tsadc->reg_lock);
> finish_wait(&tsadc->reg_se_wait, &wait);
>
> + /*
> + * Sequencer should either be idle or
> + * busy applying the charge step.
> + */
> reg = tscadc_readl(tsadc, REG_ADCFSM);
> - WARN_ON(reg & SEQ_STATUS);
> + WARN_ON(reg & SEQ_STATUS & (!CHARGE_STEP));
> tsadc->adc_waiting = false;
> }
> tsadc->adc_in_use = true;
> @@ -96,7 +100,6 @@ static void am335x_tscadc_need_adc(struct ti_tscadc_dev *tsadc)
> void am335x_tsc_se_set_once(struct ti_tscadc_dev *tsadc, u32 val)
> {
> spin_lock_irq(&tsadc->reg_lock);
> - tsadc->reg_se_cache |= val;
> am335x_tscadc_need_adc(tsadc);
>
> tscadc_writel(tsadc, REG_SE, val);
I believe all of these changes can, and therefor should live in a
separate patch.
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> index e2e70053470e..fcce182e4a35 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)
> @@ -127,6 +128,7 @@
>
> /* Sequencer Status */
> #define SEQ_STATUS BIT(5)
> +#define CHARGE_STEP 0x11
>
> #define ADC_CLK 3000000
> #define TOTAL_STEPS 16
The header changes should be split between the two Input and MFD
patches.
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
