On Sun, 22 Sep 2019 10:50:16 -0700 Gwendal Grignou <[email protected]> wrote:
> EC FIFO can send sensor events in batch. Spread them based on > previous (TSa) and currnet timestamp (TSb) > > EC FIFO iio events > +-----------+ > | TSa | > +-----------+ +---------------------------------------+ > | event 1 | | event 1 | TSb - (TSb - TSa)/n * (n-1) | > +-----------+ +---------------------------------------+ > | event 2 | | event 2 | TSb - (TSb - TSa)/n * (n-2) | > +-----------+ +---------------------------------------+ > | ... | ------> | .... | | > +-----------+ +---------------------------------------+ > | event n-1 | | event 2 | TSb - (TSb - TSa)/n | > +-----------+ +---------------------------------------+ > | event n | | event 2 | TSb | > +-----------+ +---------------------------------------+ > | TSb | > +-----------+ > > Signed-off-by: Gwendal Grignou <[email protected]> Looks fine to me and the docs are nice :) Timestamps for batches are always a pita. Reviewed-by: Jonathan Cameron <[email protected]> > --- > .../platform/chrome/cros_ec_sensorhub_ring.c | 99 ++++++++++++++++++- > 1 file changed, 96 insertions(+), 3 deletions(-) > > diff --git a/drivers/platform/chrome/cros_ec_sensorhub_ring.c > b/drivers/platform/chrome/cros_ec_sensorhub_ring.c > index 8cd533d5542e..48327e80a5a3 100644 > --- a/drivers/platform/chrome/cros_ec_sensorhub_ring.c > +++ b/drivers/platform/chrome/cros_ec_sensorhub_ring.c > @@ -160,6 +160,97 @@ static bool cros_ec_ring_process_event( > return true; > } > > +/* > + * cros_ec_ring_spread_add: Calculate proper timestamps then > + * add to ringbuffer (legacy). > + * > + * If there is a sample with a proper timestamp > + * timestamp | count > + * older_unprocess_out --> TS1 | 1 > + * TS1 | 2 > + * out --> TS1 | 3 > + * next_out --> TS2 | > + * We spread time for the samples [older_unprocess_out .. out] > + * between TS1 and TS2: [TS1+1/4, TS1+2/4, TS1+3/4, TS2]. > + * > + * If we reach the end of the samples, we compare with the > + * current timestamp: > + * > + * older_unprocess_out --> TS1 | 1 > + * TS1 | 2 > + * out --> TS1 | 3 > + * We know have [TS1+1/3, TS1+2/3, current timestamp] > + */ > +static void cros_ec_ring_spread_add( > + struct cros_ec_sensorhub *sensorhub, > + unsigned long sensor_mask, > + s64 current_timestamp, > + struct cros_ec_sensors_ring_sample *last_out) > +{ > + struct cros_ec_sensors_ring_sample *out; > + int i; > + > + for_each_set_bit(i, &sensor_mask, BITS_PER_LONG) { > + s64 older_timestamp; > + s64 timestamp; > + struct cros_ec_sensors_ring_sample *older_unprocess_out = > + sensorhub->ring; > + struct cros_ec_sensors_ring_sample *next_out; > + int count = 1; > + > + for (out = sensorhub->ring; out < last_out; out = next_out) { > + s64 time_period; > + > + next_out = out + 1; > + if (out->sensor_id != i) > + continue; > + > + /* Timestamp to start with */ > + older_timestamp = out->timestamp; > + > + /* find next sample */ > + while (next_out < last_out && next_out->sensor_id != i) > + next_out++; > + > + if (next_out >= last_out) { > + timestamp = current_timestamp; > + } else { > + timestamp = next_out->timestamp; > + if (timestamp == older_timestamp) { > + count++; > + continue; > + } > + } > + > + /* > + * The next sample has a new timestamp, > + * spread the unprocessed samples. > + */ > + if (next_out < last_out) > + count++; > + time_period = div_s64(timestamp - older_timestamp, > + count); > + > + for (; older_unprocess_out <= out; > + older_unprocess_out++) { > + if (older_unprocess_out->sensor_id != i) > + continue; > + older_timestamp += time_period; > + older_unprocess_out->timestamp = > + older_timestamp; > + } > + count = 1; > + /* The next_out sample has a valid timestamp, skip. */ > + next_out++; > + older_unprocess_out = next_out; > + } > + } > + > + /* push the event into the kfifo */ > + for (out = sensorhub->ring; out < last_out; out++) > + cros_sensorhub_send_sample(sensorhub, out); > +} > + > /* > * cros_ec_sensorhub_ring_handler - the trigger handler function > * > @@ -280,9 +371,11 @@ static void cros_ec_sensorhub_ring_handler(struct > cros_ec_sensorhub *sensorhub) > } > } > > - /* push the event into the kfifo */ > - for (out = sensorhub->ring; out < last_out; out++) > - cros_sensorhub_send_sample(sensorhub, out); > + /* > + * Spread samples in case of batching, then add them to the ringbuffer. > + */ > + cros_ec_ring_spread_add(sensorhub, sensor_mask, > + current_timestamp, last_out); > > ring_handler_end: > sensorhub->fifo_timestamp[LAST_TS] = current_timestamp;
