mfd: ti_am335x_tscadc: Fix TSC operation after ADC continouous mode

commit 6ac734d2242949f41eb1346ca0fd4ed010c937aa upstream.

After enabling and disabling ADC continuous mode via sysfs, ts_print_raw
fails to return any data. This is because when ADC is configured for
continuous mode, it disables touch screen steps.These steps are not
re-enabled when ADC continuous mode is disabled. Therefore existing values
of REG_SE needs to be cached before enabling continuous mode and
disabling touch screen steps and enabling ADC steps. The cached value
are to be restored to REG_SE once ADC is disabled.

Fixes: 7ca6740cd1cd ("mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization")

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
index d4e8604..e3076af 100644 (file)
--- a/drivers/mfd/ti_am335x_tscadc.c
+++ b/drivers/mfd/ti_am335x_tscadc.c
@@ -54,7 +54,7 @@ void am335x_tsc_se_set_cache(struct ti_tscadc_dev *tsadc, u32 val)
        unsigned long flags;
 
        spin_lock_irqsave(&tsadc->reg_lock, flags);
-       tsadc->reg_se_cache = val;
+       tsadc->reg_se_cache |= val;
        if (tsadc->adc_waiting)
                wake_up(&tsadc->reg_se_wait);
        else if (!tsadc->adc_in_use)
@@ -97,6 +97,7 @@ 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);