linux-next/drivers/iio/trigger
Fabrice Gasnier 77a9febfd8 iio: stm32 trigger: fix sampling_frequency read
When prescaler (PSC) is 0, it means div factor is 1: counter clock
frequency is equal to input clk / (PSC + 1).
When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
This is handled in frequency write routine, by writing respectively:
- prescaler - 1 to PSC
- reload value - 1 to ARR
This fix does the opposite when reading the frequency from PSC and ARR:
- prescaler is PSC + 1
- reload value is ARR + 1

Thus, PSC may be 0, depending on requested sampling frequency (div 1).
In this case, reading freq wrongly reports 0, instead of computing and
reporting correct value.
Remove test on !psc and !arr.

Small test on stm32f4 (example on tim1_trgo), before this fix:
$ cd /sys/bus/iio/devices/triggerX
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
0

After this fix:
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
10000

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
2017-04-08 16:35:08 +01:00
..
iio-trig-hrtimer.c ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
iio-trig-interrupt.c iio: trigger: free trigger resource correctly 2017-01-22 16:14:21 +00:00
iio-trig-loop.c iio:trigger: Experimental kthread tight loop trigger (thread only) 2016-06-03 13:18:44 +01:00
iio-trig-sysfs.c iio: trigger: free trigger resource correctly 2017-01-22 16:14:21 +00:00
Kconfig iio: Add STM32 timer trigger driver 2017-01-25 16:11:56 +00:00
Makefile iio: Add STM32 timer trigger driver 2017-01-25 16:11:56 +00:00
stm32-timer-trigger.c iio: stm32 trigger: fix sampling_frequency read 2017-04-08 16:35:08 +01:00