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iio: adc: at91_adc: correct default shtim value 

When sample_hold_time is zero (this is the case when DT is not used or if
atmel,adc-sample-hold-time is omitted), then the calculated shtim is large.

Make that 0, which is the default for that register and the ADC will then use a
sane value of 2/ADCCLK or 1/ADCCLK depending on the version.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Alexandre Belloni 2014-03-03 18:07:00 +00:00 committed by Jonathan Cameron
parent 301841a634
commit 8f32b6ba56
1 changed files with 5 additions and 2 deletions
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7
drivers/iio/adc/at91_adc.c
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@ -1007,8 +1007,11 @@ static int at91_adc_probe(struct platform_device *pdev)
* the best converted final value between two channels selection
* The formula thus is : Sample and Hold Time = (shtim + 1) / ADCClock
*/
shtim = round_up((st->sample_hold_time * adc_clk_khz /
1000) - 1, 1);
if (st->sample_hold_time > 0)
shtim = round_up((st->sample_hold_time * adc_clk_khz / 1000)
- 1, 1);
else
shtim = 0;
reg = AT91_ADC_PRESCAL_(prsc) & st->registers->mr_prescal_mask;
reg |= AT91_ADC_STARTUP_(ticks) & st->registers->mr_startup_mask;