4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
commit 7531cf59bfa082769887ec70c2029838ea139f11 upstream.
When doing successive oversampling settings, it may fail to update filter
parameters silently:
- First time oversampling is being set, it will be successful, as fl->res
is 0 initially.
- Next attempts with various oversamp value may return 0 (success), but
keep previous filter parameters, due to 'res' never reaches above or
equal current 'fl->res'.
This is particularly true when setting sampling frequency (that relies on
oversamp). Typical failure without error:
- run 1st test @16kHz samp freq will succeed
- run new test @8kHz will succeed as well
- run new test @16kHz (again): sample rate will remain 8kHz without error
Fixes: e2e6771c6462 ("IIO: ADC: add STM32 DFSDM sigma delta ADC support")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iio/adc/stm32-dfsdm-adc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -144,6 +144,7 @@ static int stm32_dfsdm_set_osrs(struct s
* Leave as soon as if exact resolution if reached.
* Otherwise the higher resolution below 32 bits is kept.
*/
+ fl->res = 0;
for (fosr = 1; fosr <= DFSDM_MAX_FL_OVERSAMPLING; fosr++) {
for (iosr = 1; iosr <= DFSDM_MAX_INT_OVERSAMPLING; iosr++) {
if (fast)
@@ -193,7 +194,7 @@ static int stm32_dfsdm_set_osrs(struct s
}
}
- if (!fl->fosr)
+ if (!fl->res)
return -EINVAL;
return 0;
