On Sat, 2 Dec 2017 11:49:49 +0000 Jonathan Cameron jic23@kernel.org wrote:
On Mon, 27 Nov 2017 12:51:48 +0100 Arnd Bergmann arnd@arndb.de wrote:
getnstimeofday() suffers from the overflow in y2038 on 32-bit architectures and requires a conversion into the nanosecond format that we want here.
This changes ssp_parse_dataframe() to use ktime_get_real_ns() directly, which does not have that problem.
An open question is what time base should be used here. Normally timestamps should use ktime_get_ns() or ktime_get_boot_ns() to read monotonic time instead of "real" time, which suffers from time jumps due to settimeofday() calls or leap seconds.
Signed-off-by: Arnd Bergmann arnd@arndb.de
+cc Karol Wrona.
Fix looks fine to me, but might be nice to address that and the question of using a monotonic clock all in one go.
This is probably a copy of an ancient piece of my stupidity where I used the wrong clock for the core IIO timestamping code. We fixed that a while back by letting the user chose the clock. If you are running slow enough you actually do want the 'real' time - probably never the case here though.
If we don't hear from Karol for a few weeks I'll pick this up and we can address the wrong timestamp sometime in the future!
Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders to play with it.
Thanks,
Jonathan
Jonathan
drivers/iio/common/ssp_sensors/ssp_spi.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/iio/common/ssp_sensors/ssp_spi.c b/drivers/iio/common/ssp_sensors/ssp_spi.c index 704284a475ae..2ab106bb3e03 100644 --- a/drivers/iio/common/ssp_sensors/ssp_spi.c +++ b/drivers/iio/common/ssp_sensors/ssp_spi.c @@ -277,12 +277,9 @@ static int ssp_handle_big_data(struct ssp_data *data, char *dataframe, int *idx) static int ssp_parse_dataframe(struct ssp_data *data, char *dataframe, int len) { int idx, sd;
- struct timespec ts; struct ssp_sensor_data *spd; struct iio_dev **indio_devs = data->sensor_devs;
- getnstimeofday(&ts);
- for (idx = 0; idx < len;) { switch (dataframe[idx++]) { case SSP_MSG2AP_INST_BYPASS_DATA:
@@ -329,7 +326,7 @@ static int ssp_parse_dataframe(struct ssp_data *data, char *dataframe, int len) } if (data->time_syncing)
data->timestamp = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
data->timestamp = ktime_get_real_ns();return 0; }
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