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SubjectRe: [PATCH v7 00/12] Cros EC sensor hub FIFO support
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Hi Gwendal,

On 27/3/20 23:34, Gwendal Grignou wrote:
> This patchset adds a sensorhub driver for spreading sensor
> events coming from the Embedded controller sensor FIFO:
>
> +---------------+ +--------------+ +----
> | cros_ec_accel | | cros_ec_gyro | | ...
> +---------------+ +--------------+ +----
> id:0 \ id:1 | / id:..
> +------------------------------+
> | cros-ec-sensorhub |
> +------------------------------+
> | cros_ec_dev |
> +------------------------------+
> | cros_ec_i2c, cros_ec_lpc, .. |
> +------------------------------+
> |
> EC
>
> When new sensors events are present, the EC raises and interrupt,
> sensorhub reads the FIFO and uses the 'id' field to spread the event to
> the proper IIO sensors. This stack is similar to the HID sensor input
> stack.
>
> The patch set allows the host to receive MEMS sensor sample
> asynchronously from ChromeOS Emebedded Controller (EC).
>
> Given the EC and the host are not synchronized, the timestamp generated
> by the EC drifts and the AP interrupt latency adds variable delay.
>
> When events arrive, the driver stores the time of the interrupt and use
> that information to convert the timestamp from the EC time domain to the
> AP time domain. To prevent the errors from the interrupt time variation,
> a median filter smooth the timestamp generation and prevents timestamps
> to go in the past.
>
> When a batch of sensor events arrives, the sensor hub ring code spreads
> the timestamps.
>
> The buffer interaface is presentid through the IIO ABI.
> And extra parameter - flush - (presents on HID and ST sensor hub implementation)
> force the EC to send accumulated events in its queue, without waiting
> for buffer hwfifo_timeout to expire.
>
> To access sensor data, we can use iio_readdev like:
> iio_readdev -T 10000 -s 4 -b 2 iio:device4
>
> When FIFO is not supported by the EC, a trigger is present in the
> directory. After registering a trigger, setting sampling_frequency,
> the latest data collected by the sensor will be retrieved by the host
> when the trigger expires.
>
> When cros_ec_accel_legacy driver is used, no FIFO is supported and the
> sampling frequency for the accelerometers is hard coded at 10Hz.
>
> Gwendal Grignou (12):
> platform: chrome: sensorhub: Add the number of sensors in sensorhub
> platform: chrome: sensorhub: Add FIFO support
> platform: chrome: sensorhub: Add code to spread timestmap
> platform: chrome: sensorhub: Add median filter
> iio: cros_ec: Move function description to .c file
> iio: expose iio_device_set_clock
> iio: cros_ec: Register to cros_ec_sensorhub when EC supports FIFO
> iio: cros_ec: Remove pm function
> iio: cros_ec: Expose hwfifo_timeout
> iio: cros_ec: Report hwfifo_watermark_max
> iio: cros_ec: Use Hertz as unit for sampling frequency
> iio: cros_ec: flush as hwfifo attribute
>
> drivers/iio/accel/cros_ec_accel_legacy.c | 8 +-
> .../cros_ec_sensors/cros_ec_lid_angle.c | 3 +-
> .../common/cros_ec_sensors/cros_ec_sensors.c | 13 +-
> .../cros_ec_sensors/cros_ec_sensors_core.c | 403 +++++--
> drivers/iio/industrialio-core.c | 8 +-
> drivers/iio/light/cros_ec_light_prox.c | 15 +-
> drivers/iio/pressure/cros_ec_baro.c | 14 +-
> drivers/platform/chrome/Makefile | 4 +-
> drivers/platform/chrome/cros_ec_sensorhub.c | 111 +-
> .../platform/chrome/cros_ec_sensorhub_ring.c | 1046 +++++++++++++++++
> .../linux/iio/common/cros_ec_sensors_core.h | 104 +-
> include/linux/iio/iio.h | 2 +
> .../linux/platform_data/cros_ec_sensorhub.h | 163 +++
> 13 files changed, 1655 insertions(+), 239 deletions(-)
> create mode 100644 drivers/platform/chrome/cros_ec_sensorhub_ring.c
>

Queued patches from 0 to 11 to for-next. Patch 12 needs some rework.

Thanks,
Enric

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