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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2013-12-19 16:28:29 +0100
committerLee Jones <lee.jones@linaro.org>2014-01-07 08:41:15 +0000
commit7e170c6e4f7501bea900aa66b2b27a6ce5001e25 (patch)
tree76eea8291945b24d8bbbf215243f7239c9728a08 /drivers/iio
parent3466bd2273b81a0a29d0e134ba1c78b64b84f40b (diff)
downloadlinux-7e170c6e4f7501bea900aa66b2b27a6ce5001e25.tar.bz2
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>
Diffstat (limited to 'drivers/iio')
-rw-r--r--drivers/iio/adc/ti_am335x_adc.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index ce8d03ac900f..95eef8e89979 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -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) {