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Commit 7e170c6e authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Lee Jones
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mfd: ti_am335x_tscadc: Don't read back REG_SE 



The purpose of reg_se_cache has been defeated. It should avoid the
read-back of the register to avoid the latency and the fact that the
bits are reset to 0 after the individual conversation took place.

The reason why this is required like this to work, is that read-back of
the register removes the bits of the ADC so they do not start another
conversation after the register is re-written from the TSC side for the
update.
To avoid the not required read-back I introduce a "set once" variant which
does not update the cache mask. After the conversation completes, the
bit is removed from the SE register anyway and we don't plan a new
conversation "any time soon". The current set function is renamed to
set_cache to distinguish the two operations.
This is a small preparation for a larger sync-rework.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: default avatarJonathan Cameron <jic23@kernel.org>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent 3466bd22

drivers/iio/adc/ti_am335x_adc.c

+2 −2
Original line number Diff line number Diff line
@@ -181,7 +181,7 @@ static int tiadc_buffer_postenable(struct iio_dev *indio_dev) 
		enb |= (get_adc_step_bit(adc_dev, bit) << 1);

	adc_dev->buffer_en_ch_steps = enb;



	am335x_tsc_se_set(adc_dev->mfd_tscadc, enb);

	am335x_tsc_se_set_cache(adc_dev->mfd_tscadc, enb);



	tiadc_writel(adc_dev,  REG_IRQSTATUS, IRQENB_FIFO1THRES

				| IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW);
@@ -332,7 +332,7 @@ static int tiadc_read_raw(struct iio_dev *indio_dev, 
		return -EBUSY;



	step_en = get_adc_step_mask(adc_dev);

	am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);

	am335x_tsc_se_set_once(adc_dev->mfd_tscadc, step_en);



	/* Wait for ADC sequencer to complete sampling */

	while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {

drivers/input/touchscreen/ti_am335x_tsc.c

+2 −2
Original line number Diff line number Diff line
@@ -198,7 +198,7 @@ static void titsc_step_config(struct titsc *ts_dev) 
	/* The steps1 … end and bit 0 for TS_Charge */

	stepenable = (1 << (end_step + 2)) - 1;

	ts_dev->step_mask = stepenable;

	am335x_tsc_se_set(ts_dev->mfd_tscadc, ts_dev->step_mask);

	am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);

}



static void titsc_read_coordinates(struct titsc *ts_dev,
@@ -322,7 +322,7 @@ static irqreturn_t titsc_irq(int irq, void *dev) 


	if (irqclr) {

		titsc_writel(ts_dev, REG_IRQSTATUS, irqclr);

		am335x_tsc_se_set(ts_dev->mfd_tscadc, ts_dev->step_mask);

		am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask);

		return IRQ_HANDLED;

	}

	return IRQ_NONE;

drivers/mfd/ti_am335x_tscadc.c

+12 −4
Original line number Diff line number Diff line
@@ -53,24 +53,32 @@ static void am335x_tsc_se_update(struct ti_tscadc_dev *tsadc) 
	tscadc_writel(tsadc, REG_SE, tsadc->reg_se_cache);

}



void am335x_tsc_se_set(struct ti_tscadc_dev *tsadc, u32 val)

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 = tscadc_readl(tsadc, REG_SE);

	tsadc->reg_se_cache |= val;

	am335x_tsc_se_update(tsadc);

	spin_unlock_irqrestore(&tsadc->reg_lock, flags);

}

EXPORT_SYMBOL_GPL(am335x_tsc_se_set);

EXPORT_SYMBOL_GPL(am335x_tsc_se_set_cache);



void am335x_tsc_se_set_once(struct ti_tscadc_dev *tsadc, u32 val)

{

	unsigned long flags;



	spin_lock_irqsave(&tsadc->reg_lock, flags);

	tscadc_writel(tsadc, REG_SE, tsadc->reg_se_cache | val);

	spin_unlock_irqrestore(&tsadc->reg_lock, flags);

}

EXPORT_SYMBOL_GPL(am335x_tsc_se_set_once);



void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val)

{

	unsigned long flags;



	spin_lock_irqsave(&tsadc->reg_lock, flags);

	tsadc->reg_se_cache = tscadc_readl(tsadc, REG_SE);

	tsadc->reg_se_cache &= ~val;

	am335x_tsc_se_update(tsadc);

	spin_unlock_irqrestore(&tsadc->reg_lock, flags);

include/linux/mfd/ti_am335x_tscadc.h

+2 −1
Original line number Diff line number Diff line
@@ -176,7 +176,8 @@ static inline struct ti_tscadc_dev *ti_tscadc_dev_get(struct platform_device *p) 
	return *tscadc_dev;

}



void am335x_tsc_se_set(struct ti_tscadc_dev *tsadc, u32 val);

void am335x_tsc_se_set_cache(struct ti_tscadc_dev *tsadc, u32 val);

void am335x_tsc_se_set_once(struct ti_tscadc_dev *tsadc, u32 val);

void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val);



#endif