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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c b/drivers/input/touchscreen/ti_am335x_tsc.c
index 68beada..2ca5a7be 100644
--- a/drivers/input/touchscreen/ti_am335x_tsc.c
+++ b/drivers/input/touchscreen/ti_am335x_tsc.c
@@ -198,7 +198,7 @@
/* 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 @@
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;
